Org mode, stored in Git, stored in Dropbox. (Git is used mainly so I can roll back a config change when I screw something up through tinkering with my setup).

Org mode, stored in Git, stored in Dropbox. (Git is used mainly so I can roll back a config change when I screw something up through tinkering with my setup). I love the free form nature of org mode, but its killer features for me are - really easy to pull out lists of tasks, no matter where they are, or how deeply they're nested - ability to track time info directly against tasks, and then automatically generate timesheet info