Common problem to RTM and calendar apps (or maybe I'm the problem?): I feel like I need an option to keep sending me a reminder every once in a while until I complete certain tasks. These are tasks that I want to do soon, that I might otherwise forget about, but that don't actually have a fixed deadline.
Remember the Milk
Not OSS, but has some definite advantages: very quick, offline support with Gears, API.
More GTD-centric client?
Traceability? It looks like completed tasks are kept forever.
Needs a quicker way to add lists
I was thinking of sub-tasks, but I guess that probably means the "super-tasks" should actually be projects
GTD (p. 137) suggests that you may start with somewhere around 30-100 projects. How well will RTM scale to this number, and what about all the archived projects there will be in the future?
Doesn't seem to add new projects (added elsewhere) until you refresh the browser
Tracks - it looks like I'll probably try this or Chandler
Lots of statistics available
Wasn't as easy as expected to set up, manual isn't very good, no real instructions on how to serve with Apache
Chandler - it does sound awfully cool, though when I think of Java I think of high memory usage. Standalone app and server (for synchronization with standalone app and for web use) are free open source. It looks like they've done some research and have a theory and plan for how things should be done.