In my last post I gave my first impressions of the BT eFrame1000 – a wifi equipped digital photo frame, and I hinted that I’d started to investigate how to exploit a feature that’s intended for streaming Flickr photo albums so that I could view information from other sites. So far, I’ve had some success at cajoling the frame into displaying pictures from sites other than Flickr, and showing news and weather updates. Here’s how…

Background

The eFrame 1000 has a feature that can be configured (via the Windows PC software) with URLs for Flickr photo albums. Once configured, you can go to the frame and select Photos > Flickr > [Album Name] to stream the photos in that album directly from Flickr over your wireless network without needing a computer to be switched on. All references to this feature on the frame, the PC software and in the documentation specifically refer to Flickr and Flickr only (I suspect that’s because Yahoo! (who own Flickr) have a partnership with BT who make the frame and the two companies co-brand some of their broadband products). This feature works because each public album/stream/group on flickr has an RSS url that users can subscribe to in order to see the 20 most recent uploads.

Non-Flickr feeds

A flickr RSS feed contains a link to each image (and a smaller thumbnail version). It turns out that although it’s not a documented feature, you can configure the frame to use any RSS feed that’s in the correct format and the frame won’t care that it isn’t coming from flickr.com. Be warned though, you can’t just take a regular RSS news feed, it has to be a feed where every item contains an embedded image in the same format used by Flickr e.g:

<media:content url="http://farm4.static.flickr.com/3483/3290803901_527112a24e_o.jpg"
type="image/jpeg"
height="1920"
width="2560"/>
<media:thumbnail url="http://farm4.static.flickr.com/3483/3290803901_9178782db5_s.jpg"
height="75"
width="75" />

I haven’t yet determined whether the media:thumbnail tag is used.

Frame Channel

The best site so far has been FrameChannel.com. This is a service designed for wifi picture frames whereby a user creates their own channel by subscribing to “widgets”. It’s intended for framechannel specific frames that will make full use of their API to control slideshow speed, transitions, order etc, but they also provide an RSS feed in a format that works with the eFrame. So, if you subscribe to a weather report, you configure the widget on the frame channel website with your location and then the RSS feed for you channel will contain an image that is created by the weather widget to show your local forecast. Similarly the reuters news widget will generate an image in the feed containing a brief headline and associated picture. The RSS feed is a little hidden away so here’s how you find it: Sign in to your framechannel account. Configure your channel. Go to “My Account”. Copy the feed url that appears just below the tab bar into your browsers address bar and load the feed. Then drag the url from your address bar into the flickr feed url box in the eFrame software and click “Update”  – that will download the configuration to your frame. Then in future on your frame you can go to Photos > Flickr  and you’ll see an album named something like “FrameChannel content for…”.

Other sites

I’ve had some success at finding other sites that work with the eFrame. I’ll keep the list below up-to-date as I find others.

Tick/Cross images from FamFamFam Silk library.

Potential Gotchas

I had a few issues with the PC software for the eFrame in that when I tried to load a feed that it didn’t like, it then subsequently failed to accept any other feeds (even valid ones) and just failed silently without any error message. I had to shutdown the sofware (from the system tray) and restart before it would start accepting new feeds again.

This week I bought a digital photo frame. I’ve been tempted to get one of these for a while but been put off until now for a few reasons:

• The “affordable” screens are either very small or very low resolution (or both).
• I run XBMC on my old Xbox so can view every photo I’ve ever taken on the 37″ LCD in the living room anyway.
• Cropping and copying images to a memory card and transferring to the frame seemed like too much hassle.

Frames equipped with WiFi provide a solution to the issue of transferring images to the frame and have been around for a while now but are usually expensive and often tied to a specific photo sharing site or need an ongoing subscription. Enter the BT eFrame 1000 which until recently was £130, but last week I noticed has been reduced to just under £40 (less if you happen to work for said company and get an extra few pounds staff discount, ahem! End of disclaimer). At that price it’s comparable to the run-of-the mill unbranded, low-res screens and I decided was worth a punt. It arrived yesterday and here are my initial thoughts…

Screen quality

At the end of the day this is what really matters – all the fancy features in the world would be a waste of time if the pictures looked awful right?. Fortunately they don’t. The screen 800×600 resolution which is pretty high for an 8″digital photo frame and the images look really great – very crisp, and very bright (perhaps aided by the matt black surround).

Appearance

The matt black frame may not suit everyone (and is quite wide at 1.5″) and is unfortunately not interchangeable. However it’s quite subtle and I’m tempted to try mounting it inside a nice large wooden frame anyway to disguise it further. An added bonus is that BT chose not to emblazen the frame with any logos, graphics or text as many other manufacturers do. There’s a small IR receiver embedded in the surround below the screen for the remote control, 6 buttons on the top edge of the screen for power and menu navigation, and on the right edge is the card reader (CF/SD/MMC/MS(pro)), a USB port (for viewing images on a memory stick), a mini USB port (for connecting to the PC to download images to the frame), and the power connector. One thing I noticed about the position of the power connector is that the power cable sticks out slightly on the right-edge of the frame so is visible from the front – it should really have either been positioned on the back of the frame, or the power cable should be fitted with an elbow so that the trailing cable can’t be seen from the front.

Features

The frame displays photos in JPG format as you’d expect (I haven’t tried other formats) and will play back mp3 audio files. I haven’t tried video yet, but it’s not listed as a feature so I don’t expect it to work. Pictures and audio can be played back from the onboard 128MB memory; from a memory card in the card reader or usb port; and can be streamed from a shared folder on your network (which required the included Windows-only software to be installed). In addition, it can load images from a public Flickr RSS feed (a Windows PC is needed for the initial configuration but after that the PC doesn’t need to be running). I’ve been able to exploit this feature to stream images and news/weather info from a range of other sites (more about that in my next post). One note about public Flickr RSS feeds: because the frame doesn’t log in to your flickr account it can only retrieve public feeds, and Flickr will only return the 20 most recent images in their public feeds so even if you have thousands of images in a flickr-pro account, don’t expect to be able to view more than the most recent 20 uploads.

Navigation

Menus are clear, the UI is clean and consistent with heavy use of a standard icon theme that is appearing on lots of the BT’s websites and products (I’m thinking of the HomeHub and BroadbandAnywhere mobile handsets in particular) and the navigation is generally pretty good all-round. You drill down into menus with the right arrow, use the left arrow to go back and up/down keys to scroll though the current menu (OK to select). The area that really lets it down is the use of the buttons on the supplied remote control. There are 3 menu buttons labelled A, B and C which have different (and inconsistent) functions depending on your current operation: The C button is often used as Cancel  but in a slideshow will rotate the current image rather than quit the slideshow (that would be the left-arrow) for example.

Performance

I haven’t timed any operations or had time to really thrash the frame but it has a generally responsive feel so far. Menus respond quickly, images can be rotated in a couple of seconds (though zooming seems to take a little longer). There are no slick sliding iPhone-esque menus here, but I guess it’s only equipped with a relatively modest processor. Streaming images from the local network or internet feels like it takes a comparable amount of time to what it would take to load the same image on a PC (i.e. the frame isn’t adding noticeable additional delays). It could be faster of course, but it doesn’t feel overly sluggish under normal operation.

PC Software

The PC software is used to configure the frame to view Flickr albums or local network shares and can also be used to copy images to the frames internal storage. Some will complain that the software is windows only, but that’s not been a problem for me. The windows software looks good (slick glass-effect buttons carried over from the UI on the frame itself) but it has a few annoying traits: it’s set to be always-on-top and that can’t be disabled. When you hit the close icon, it only minimises to the system tray. Then when you click to “Manage Flickr Albums” it opens the flickr website in a browser but it’s always InternetExplorer even though Firefox is already running and is my default browser. If I go back and forth between the main menu and the Flickr setup screen, it will open the flickr website in a new IE window every single time.

Hackability

Ok I admit that this is more applicable to me that it would be to the average user of the frame… So far, I’ve tried opening a web browser, an ftp and a telnet connection directly to the frame’s IP address but not had any luck yet. There are a few port numbers listed in an ini file sitting in the application’s install folder which will be my next angle of investigation. My biggest success so far has been in getting the frame to show news and weather reports by configuring it with RSS urls for sites other than Flickr – I write more on this in my next post but I’m quite excited by the possibilities that this could offer. Potentially I could use the frame to read my twitter stream, or local traffic conditions, or stock alerts. Actually I think BT have missed a big opportunity here because they could use the frame in conjunction with their other products – e.g. as a program guide for the Vision TV service, to view a list of missed calls and messages on my landline or to view stats about my recent calls (duration, distance, time of day, cost).

Overall

At this price point it’s difficult to find any serious faults that I can’t live with. Perhaps the biggest let-down is the PC software but once the frame has been set up, I’m unlikely to use the PC software very often anyway. It’s only been 2 days, but so far I’m happy with my purchase.

It’s taken me a while I’ll admit but I’ve just got around to releasing the sourcecode for the XBMChumby widget I wrote which displays the XBMC “Now Playing” queue on the Chumby. I decided early on that my very basic skills as a flash/ActionScript developer weren’t up to developing this to it’s full potential so now if anyone is interested in taking it further please checkout the code and get in touch if you have any problems building it etc etc etc.

The sourceforge project page is: https://sourceforge.net/projects/xbmchumby/

…or you can point your CVS client at xbmchumby.cvs.sourceforge.net

I ordered an HTC S710 last week (arrived Friday) on the BT Total Broadband Anywhere package. It’s a Windows Mobile 6 Standard smartphone (no touch screen, but a nice slide-out qwerty keyboard). I’ve used the PocketPC OS before on PDAs but never on a phone and so I had the obvious concerns about running a version of Windows on my main handset. Initially the responsiveness of some of the menus seemed a bit slow and accessing some of the common features like “compose new message” seemed more long-winded than I’ve been used to (I’ve been exclusively a SonyEricsson user for the past few years). After a few days use I’m starting to know my way around the menus though, I’m finding ways to customise the interface with shortcuts and I’ve installed a few new apps to provide the functionality I want.

I plan to post more feedback on the S710, Windows Mobile 6 and any useful software/hints/tips over the coming weeks. If you’re interested, you can view all S710 posts or subscribe to a feed.

Disclosure: Yes, I happen to work for BT, but I’m not directly involved in the Total Broadband Anywhere project and the opinions expressed here are entirely my own. 

Intro
I’ve created a Chumby widget to act as a basic remote display for XBMC. I’ve been using it and reworking it over the last couple of weeks and I think it’s now in a state where I can make it available for others to try. It works by retreiving an RSS feed from the Xbox that contains a list of the next 5 tracks in the music playlist. If no music is playing, the RSS feed will be empty. To achieve this I’ve written a simple web page that sits on the Xbox and uses the XBMC API to retreive information about the current playlist. The widget also uses XBMC’s http API to provide basic controls to play, pause and skip tracks. This is my first attempt at using ActionScript so the functionality is fairly basic, but if others find it useful I may add more features, or release the sourcecode.

Installation
To get the widget running, download this zip file and copy the contents to the “web” folder on your xbox (usually /e:/apps/xbmc/web). The zip contains the web page to generate the RSS and a crossdomain.xml file to make the RSS accessible from the Chumby. You may need to edit the playlist.asp file to configure the IP address of your xbox which defaults to 10.0.0.5 – you can find this from the Settings > Network Settings screen in XBMC. Also, from the settings screen in XBMC make sure that the web server is enabled and doesn’t require a password.

Next, just log in to your profile on chumby.com and add the XBMChumby widget (in the “Entertainmnet” category). The configuration widget will prompt for the IP address of your Xbox. Then just start playing some music on the Xbox and when the widget loads on the Chumby it will retrieve the RSS feed from the Xbox and show you the next 5 tracks in the playlist (along with album art for the first track). At the moment the widget only retrieves the RSS feed when it first loads so make sure that it isn’t the only widget in your channel otherwise it will never refresh.

Testing an app for the Nokia N800 to publish directly to wordpress.

I’ve been monitoring the Chumby project since I first saw the device on an episode of Diggnation over a year ago… Kevin had been given one of the alpha prototypes at FooCamp and gave a quick description. I’ve been waiting since then for the device to get a public release – I guess that shows the power of product placement even though I’m sure no cash had changed hands for it to appear on the show. People who know me or have read my thoughts on this before will know that I think there’s a lot of potential for an “ambient” device that provides up-to-date information from the online world without the user having to be sat in front of a PC. I was disappointed with the Nabaztag because of limitations with the user interface, but eager to get my hands on a Chumby as it seemed far more advanced. The Chumby was originally pitched as a new take on clock-radio for the internet enabled 21st century but I think that description groslly undersells it (and at $179, it’s an epensive way to wake up in the morning).

Put simply, the Chumby is an always on device with a 3.5″ touchscreen and a wifi connection to get online and is manufactured by Chumby Industries. It runs Linux (but without the user having to know anything about Linux), has (stereo) speakers, 2 USB ports for future expansion (or for connection to additional storage or an iPod) and built-in acelerometer that can be used by Chumby software as an input device. It’s all packaged in a padded leather housing so is squishy to hold. In fact the housing contains a “squeeze sensor” as an additional input. The great thing about the whole Chumby project though is that it’s OpenSource – that’s both software and hardware. If you’re really keen you can download the parts list and schematics and build your own Chumby from scratch!

The Chumby runs flash-lite widgets (aka gadgets, aka portlets in old money). Users log in to their account on the Chumby website, select & configure widgets from the catalogue and the device connects to Chumby.com to download it’s configuration and the actual widget swf files. Widgets can be grouped into “channels” so that the user can easily switch between widgets, and in operation the device cycles through all the widgets in the current channel (I currently have News, Games, Photos and Test channels). There’s also a “VirtualChumby” on the website so you can get a feel for the widgets before downloading to the device. The only software that’s included in the firmware is the Control Panel used to set alarms, switch channels, etc everything else is downloaded each time the device is switched on so without an internet connection it’s pretty dumb.

The device hasn’t been launched outside the US as yet (it has FCC aproval for the US but needs the equivalent for other territories) so I got mine from eBay. First impressions were very good – it comes packaged in a branded canvas bag rather than the usual moulded plastic/polystyrene and upon turning it on for the first time plays an animated flash movie with voiceover by the development team that explains exactly how to get it connected to your wifi and activated on the Chumby site. I know this experience has been rehearsed and revised through an invitation only trial launch that’s been running for a couple of months. You definitely get the feeling that this is a small dedicated company run by people who are passionate about the device rather than a big faceless corporation. I’m not normally one to read instruction manuals anyway, but the Chumby really doesn’t need one anyway – the setup was super simple and worked flawlessly.

There’s a wide range of widgets from the basic clock (I was happy to find that the obligatory binary clock widget is present) and RSS news reader to streaming audio widgets, to personalised widgets that display the latest status updates/notifications on your facebook account and the number of bids/current price of any eBay auctions you’re watching. Although Chumby Industries do provide some widgets themselves, the majority are contributed by the community so they cover a very broad spectrum from useful, to fun, to perculiar (hypnotoad?). Because the widgets are flash based they generally look very slick – probably better than could be achieved with html/javascript widgets but for me as a developer, being flash-only is a barrier to entry. I don’t know how to write flash and I don’t want to invest hundreds of pounds in Adobe Flash tools so that I can learn. There are open source compilers available that will take ActionScript source code and convert to a Flash swf and I’m playing around with those at the moment (more on that soon, in a future post). The Flash sandbox also comes with its own cross-domain policy that prevents a Flash movie on one domain from retrieving content from another domain unless the content provider hosts a crossdomain.xml file to explicitly allow it. Potentially this is harder to circumvent than the JavaScript XmlHttpRequest cross-domain policy which could be a pain for developers but is better for end users concerned about security of their data.

Chumby Industries have stated that their policy will be to roll out all software updates and new features as automatic downloads for free so that the device “will be even better next year than it is now”. This is a highly commendable policy and I applaud them for it, though it does make me wonder how they ever plan to turn a sustainable profit. The software and hardware are opensource, but the company exists to make money. They don’t charge for software updates and there’s no subscription for using the service or widgets. In theory Chumby Industries could release “premium” widgets for which they could charge but I’m sure the community would quickly develop free alternatives. Chumby Industries could inject adverts into the channels for playback between the widgets but I suspect there would be a big backlash to that approach if they introduced it now because it wasn’t part of user expectations at the start. I’m not sure how else they can monetize the Chumby except for a small overhead they might make on each device sold.

If there has been any compromise with the device it’s that its forever tethered to mains power. It has a small 9V battery just to preserve its settings but cannot operate without mains electricity. So far I’ve found that I want to move the device around: in the kitchen to catch up on news and friend statuses while cooking in the evening, in the spare room next to the computer while working, in the living room on the coffee table when listening to music etc. If it could run from an internal battery, even if only for 30-60 minutes, it would be a lot more convenient. After about 2 weeks of use, I’m still very impressed with what the folks at Chumby Industries have managed to achieve: the novely hasn’t worn off yet, I’m still using it every day and it attacts a lot of interest from everyone who sees it (though I think most dismiss is as just another of my geek toys!). Only time will tell whether the Chumby and devices like it have mass market appeal but this is the best attempt at this category of device that I’ve seen so far, and I hope it catches on.

In early December I ordered a Nokia N800 internet tablet from Play.com for the bargain price of £150 (it was later reduced to £139 – I got a £20 refund – but it’s currently listed at £169. Play.com seemed to have trouble getting hold of stock as it took about 5 weeks to arrive but after our first few weeks together, read on for my first impressions.

As a web browser…
…It’s very capable. The new 2008 Operating System has a full Mozilla based browser so it has no problems coping with css/javascript/ajax etc. It can also display flash, but video (e.g. Youtube) is choppy. The screen fits 800 pixels across its width which works well for most pages, and the device has hardware buttons for zooming in and out of the page when required. You can also drag anywhere on the page to scroll – it’s not quite responsive enough to impress Apple fans but it works well enough. The wi-fi signal strength is excellent. In fact whilst away over Christmas and “borrowing” a neighbour’s bandwidth the wireless reception outperformed my HP laptop.

As an email device…
…Again it scores highly. The preloaded email client handles plain text and html emails flawlessly. I’d liken it to Outlook Express in terms of functionality – okay it’s fairly basic and I wouldn’t want to use it as my primary email device but it’s certainly adequate for keeping me in touch when I’m away from home.

As a VOIP/IM client…
…I was impressed that the 2008 OS comes with a Skype client, which whilst I haven’t used it extensively it seemed to perform well enough. It doesn’t support video calls (yet) which is a shame as the N800 has a nifty pop out webcam on the side. I’ve also installed the Pidgin universal IM client which works with AIM/MSN/Yahoo messenger/ICQ and others and provides the basic text chat with support for smileys (at least on MSN). It also has a menu option for “File Transfers” although I’ve yet to try out that feature.

As an RSS reader…
…It works quite well. If I don’t sound convinced it’s probably because RSS has been my main use of the N800 so far and as a result I’m perhaps more critical. I initially imported an OPML file of all my feeds from my desktop reader but have since cut it down to only my most read feeds because although the performance at navigating between feeds was fine, it seems quite slow to update a large set: it first displays a progress bar saying “refreshing” which takes quite a while even over a decent wi-fi connection, but when that completes it then starts a new progress bar saying that it’s “loading” the updates. Perhaps it’s because I only update once every couple of days so there are a lot of updates to download, or perhaps it’s because it displays the progress so proiminently rather than just getting on with it in the background but I certainly think there’s room for improvement here.

As a media player…

…I’ve got a 4GB SD card in the internal memory slot so I figured I could load it up with MP3s and video podcasts to it as a media player. As a video player it’s pretty good because the screen is fantastic. I’ve converted a couple of chapters from a DVD and think I could watch a 30min to 1hour show quite comfortably. There are a couple of media player apps and it’s fair to say that none of these are finished products. Canola and UKMP look great but are lacking in terms of features to let you navigate the library easily. UKMP has a nice album art view with kinetic scrolling which is a lovely novelty but I can’t help thinking that it’s trying too hard to to copy the iPhone/touch shiny UI without getting the basics right.

As a gaming device…
…Okay so it’s not a gaming device – the hardware keys aren’t well positioned for games. But it does run MAME and Space Invaders is just as good as it ever was

As a business tool…
I didn’t buy this to use for work, but a lot of people probably will and I’d have to say that for business use it really doesn’t make the grade. I haven’t found any way to sync my calendar or contacts with Outlook (which I’d like to be able to do even as a personal/entertainment device). As far as I can tell it doesn’t do Blackberry style exchange email either. The onscreen keyboard is pretty good – it can be shown at two different sizes and has a predictive mode that will suggest words before you finish typing them. I’m currently typing this blog entry on the N800 but using a folding iGo Bluetooth keyboard. The iGo works pretty well, there’s an ever so slight lag between hitting a key and it appearing on screen but you soon get used to it (at least I did, and I type at about 35 words/min). However, occasionally (about 4 times so far while typing this), it’s as if a key gets stuck and you end up with 3 full lines of the same character before you can figure out how to make it stop. That would soon get annoying if I were to do a lot of typing. I also haven’t seen any built in document viewer for word/excel/powerpoint (or even a decent text editor) although I haven’t checked for 3rd party apps yet either. I couldn’t use it if I was out of the office for long periods but I could probably manage without my laptop for the odd day.

In summary…

To be fair, Nokia pitch the N800 as an “Internet Tablet” so you’d expect it to be a good web browser, and it is. It’s capable at many of the other things it can do although certainly not best in class. Why didn’t I go down the apple route? Well, the iPhone is too expensive for the hardware spec and I don’t want to be tied into an 18month contract. I was tempted by the iPod Touch but think I’ll wait to see what the official SDK brings. For me the N800 is appealing because it’s open and hackable from the start and well supported by the community. The new N810 is an expensive alternative when a slide-out keyboard and GPS are the main extras but for around £130 the N800 is a great device if you can live with some of the shortcomings.

I got a Nabaztag last week. It’s an wifi enabled ambient device for the home that can provide information in the form of audio, speech, or coloured lights for news updates and alerts that it downloads from the internet. I think the concept is great: a device that keeps me up-to-date with weather, traffic, email or twitter without me having to boot up my computer. The technology is quite sophisticated: the initial setup is done by holding a button for 5seconds to turn the device into a wireless access point, then connect to the access point from a computer and browse to its config pages (it doesn’t have an ethernet port). From here you configure the network settings for your wireless network and then restart it and it connects to your network and the lights glow green to indicate that it has got an internet connection. All configuration is then done from the my.nabaztag.com website.

After playing around with my Nabaztag over the weekend my initial impressions are that it has a few flaws:
- The form factor. It’s supposed to look like a rabbit, which makes it look like a kids toy and not something you want to sit on the coffee table in your living room.
-The interface. The main way that the device communicates its updates is through either text-to-speech or mp3 clips. It has some lights on the front that can be configured to glow different colours to indicate different statuses, but this is quite limited. This means that every update interrupts whatever you happen to be doing at the time. I want it to be a device that sits in the corner of the room so that I can glance at it to get very high level updates and then pick it up and interact with it to get more detail. Ambient. I don’t want it to interrupt the meal I’m eating or the film I’m watching or the conversation I’m having.

Well, so far, so bad but I haven’t got to the best part: it has an API so it’s hackable! It has a very simple REST-like API that lets you send it to sleep, wake it up, change the light colour, send it some text for it read aloud or move the position of the ears (yes, really!). This certainly makes it a more useful device for me and I applaud the manufacturers, Violet, for making the device so open. I’ve started to play around with a Netvibves UWA widget for it which I’ll post here when it does something useful (there are already several 3rd party widgets available).

I’m still undecided whether this will be a useful device for me or whether it will be heading for eBay. I’m still really keen on the Chumby (or will be, when they start shipping to the UK) which I don’t expect to suffer from some of the flaws of the Nabaztag that I’ve described here. If I can take it out of its rabbit body and put it in something a bit more attractive and use the API to create something that I’ll use regularly then it could be a winner.

One of the most interesting presentations that I attended at FoWA was by Steve Souders (High Performance Yahoo!). Steve described the work that his team have done at Yahoo! to increase page load performance which led to the (perhaps surprising) discovery that 80-90% of page load times is generally consumed by front-end activity rather than back-end business logic, database access etc. By “front-end activity” Steve is referring to activity that takes place after the initial html page is retrieved such as requesting static content, parsing css/js, and actually rendering the page. The obvious conclusion is that the biggest performance gains can be achieved not by tweaking sql queries or web server config, but by focussing on front-end performance.

As a result, Steve advocates the following “14 rules”

1. Make fewer http requests
2. Use a Content Delivery Network (CDN). E.g. Akamai
3. Specify a far-future “expires” header
4. Compress text based content with GZip of deflate (achieves approx 70% reduction in file size)
5. Place CSS imports in the HEAD section at the top of the html page. (IE won’t start to render the page until all CSS has downloaded).
6. Move all script imports to the bottom of the page. (Scripts will block rendering of the remainder of the page).
7. Avoid CSS expressions (as they are evaluated every time a browser event – mouse move, resize, key press – fires, so can run tens of thousands of times per page!)
8. Use external css and js files to take advantage of browser caching.
9. Reduce DNS lookups by hosting content in as few domains as possible
10. Minify JS and CSS (removing whitespace give approx 20% reduction)
11. Avoid redirects (as they are not cached unless they have an explicit “expires” header)
12. Remove duplicate script imports (or duplicate copies of functions in different script files)
13. Configure etags correctly (or disable if not configured)
14. Cache AJaX requests where sensible (don’t automatically append a random number to the request to bypass the caching mechanism)

I’ve been a big fan of Firebug since I started writing Javascript/AJaX but this presentation alerted me to the YSlow plugin for firebug which analyses a page and generates a rating against the 14 rules.

I highly recommend reading more about these techniques on the Yahoo! developer site, and watching Steve talk about the rules in more detail. Steve has also recently brought out a book on the subject.