I've been doing some contract work over the last few weeks and brought back to life a system that I'd used when working at an agency: Bugwarrior, Taskwarrior, and Timewarrior. It requires simple applications that are written with an awesome amount of power.
I've been a user of TaskWarrior for a long time, though not always seriously, and I recently started using TimeWarrior with it so that I can keep track of the time that I spend on tasks. This is a tale about how it all went wrong, but because of some really smart choices by the original developers, it all came back in the end.