Since its last update in October 2006, my interest in Backpack, 37signals' small organization product, shrunk massively. Other Web 2.0 applications like Vitalist seemed to be much better suited to practice Getting Things Done.
With their latest update, 37signals made some very necessary additions and improvements that are very likely to make me spend money again for a paid account. This time, not for doing GTD, but to support the work on some small projects that I can provide with to-do lists and shared documents via Backpack. Especially the new dra&drop features, page dividers and RSS feeds are brilliant if you're working together on a Backpack page in a group.