I've launched another site off this codebase: http://www.londongamelist.org/
Calendar: there's a graphical calendar view in place now, which can synchronise from iCal (and thus, indirectly, from most PDAs).
Filestore: Improvements to the upload system - in paticular fixes to handle the fact that MSIE uses some very strange mimetype declarations on file upload (image/x-png and image/pjpeg in place of image/png and image/jpeg, for example) and the ability to set icons manually (as they can't generate for Really Big images).
PHP code quality: I've turned on E_NOTICE and E_STRICT error levels on several sites using this codebase, which means I've had a fairly major task of updating code to the strict PHP5 way of doing things, and made sure all variables are pre-declared. A long task, but it should cut down on future debugging. (there are probably a few stray notices floating around this site - do let me know!)
AJAX: Many ajax tutorials advise you to use text rather than XML as your ajax page format, but also advise that you use the line
http_request.overrideMimeType('text/xml');to force the behaviour of your XMLHttpRequest object
These errors can be pretty tricky to debug, particularly when they appear as JS errors...
XSS: Nasty stuff. Cross-site scripting occurs when you accidentally let a user manipulate the content of your website, either by submitted content or URL manipulation. This codebase caught most of those tricks, but at a recent talk by Rasmus Lerdorf at PHP London I discovered one that I'd completely missed: PHP_SELF. Needless to say I've done quite a few bugfixes on that one now!
MySociety: I've recently joined the MySociety group (http://www.mysociety.org/), and submitted a few code fragments - this is probably going to be a focus of my coding efforts from here, although I'll still be working on this site's codebase, particularly if there's user interest. For a start, there's a couple of external libraries that I can now jettison, due to PHP5 improvements.
I've also been to Linux World Expo, looked at picking up some LPI and MySQL certs, bought an iPod Nano (yes, they *do* scratch far too easily, Apple!) and started listening to Podcasts. Busy life.