Mac OS X only: Personal organizer iGTD uses Getting Things Done methods to help you track your projects, tasks and contexts on your Mac desktop. While iGTD isn't as close to the GTD letter as, say, ThinkingRock, it's native Mac software with hooks into other OS X apps like Quicksilver, iBackup, Growl and a menubar entry all built-in for easy entry, processing and inbox/context access. iGTD lets yo