Actiontastic

Actiontastic aims to be a Lean Mean Action Contextifying Machine.
It is a GTD (Getting Things Done) application that allows Inbox collection (including Quicksilver support), Processing into Actions, Projects, and Contexts, and acting on these items in their Context views.

All of this is aided by filtering to show only the very next action for each Project if desired. The latest version also syncs with iCal allowing iCal-friendly PDA support, as well as iPod export.