I was just trying another web GTD-idea-powered tool Toodledo and I must say that I’m shocked by it’s rich functionality (it is free). It has all the common GTD stuff - places, contexts, folder/project with some neat addon such as time tracking, calendar etc. This is for the moment best free GTD tool I’ve seen, even better than Tracks. I must admit that for my own todo needs I’m using great MyLifeOrganized application with great sync with my Windows Mobile powered smartphone.