Getting Things Done

I’ve read (in Make vol 05) about the GTDTiddlyWiki (Getting things done wiki), I have used it a bit and I must say that it’s a really nice and useful application.
It’s a sort of notebook very usable. It’s not serverside but all take place in your browser (so you can use it offline). It’s under a BSD open source license (so it’s free).
For info, Getting Things Done is the title of a book written by D. Allen.
You really need to take a look at GTDTiddlyWiki if you don’t already know it.