For those that are interested, I've released a small php and mysql app for managing tasks and lists. It's not particularly advanced - just a few simple php tutorials thrown together, but it does support contexts, projects, and printing to 3 x 5 index cards. If you're interested, it's at:
http://taskstep.cunningtitle.co.uk

Unfortunately, I'm having a bit of a bandwidth problem at the moment, so I may have to take the site down eventually, but for the moment, it's all there.

Because it's hideously unsecure, I can't create a demo, but I have posted some screenshots. Any feedback would be much appreciated. :)

EDIT: The seperate TaskStep forums are up for those who might be interested. It just helps a bit for any problems people have.