TimeTracker puts up a list of projects, and the number of minutes worked on each. You click on the project you want to work on, and it starts counting on that. At the end of the day, it saves the collected data in a file, and you can use a script to process the data. The project has been idle for quite a while, and has spawned a host of imitations, including implementations of the same basic idea for Windows, PalmPilot, KDE, and various other contexts.
