I've now installed Tracks, and will give free access to people who I know (sorry if you're just a reader!). If this applies to you, then contact me if you want an account. So far, I like it. The contexts are nice and customisable (though thought must be given, an item can only have one context). In my case I bring work home so things that can ONLY happen at work have a context 'work', things which can only happen at home have a context... you guessed it. There is a third context for work that commutes.
As well as xml feeds and calendar feeds, there are plaintext feeds which means that the thing is useful away from the computer. Each day, a new list can be printed, and at the next opportunity I can tick the boxes on screen, enter any new items and then print a clean version using the text feed. Nice.
One thing that's missing, I don't seem to be able to make use of multi-user capability as I'd like. E.g. for 'home' contexts, it woud be nice to share this context with da wife, with us both able to add and complete items. Overall, this is pretty minor.
It's nice and easy to use, the hardest bit is getting it started - entering all the information.
I think I'll just enter the info 'as and when' and get it up to speed gradually, rather than having one marathon data entering session.