External Links

GTD, the Science behind Stress-Free Productivity: very interesting university research paper comparing latest brain research and GTD principles.
43 Folders: 43 Folders is Merlin Mann's site about personal productivity, life hacks, and simple ways to make your life a little better.
43 Folders interviews of David Allen by Merlin Mann (interesting to hear their voices after reading so much written by them), can be downloaded;
Next Action verbs list from 43Folders;
Pocketmod Free disposable Personal organizer;
re:PocketMod reinventing paper organizer;
D*I*Y Planner: a set of free do-it-yourself templates, covers, documentation and other gear for creating your own highly customised paper planner system.

Mantis bug tracker: used internally to track all feedbacks, bugs, change requests, etc;
Wink Tutorial and Presentation creation software: was used to create the demonstrations.