Hamster
http://projecthamster.org
I think this should be in the repository because it is a great tool for quickly tracking tasks that you are working on. I work for two different companies and I find this application very useful for tracking when one job interrupts the other and I need to make that time up at a later point. I don't see any software that directly relates to this one. The most similar would be Go For It! But this software doesn't track the amount of time spent on tasks, it is just a simple checklist application.
Is it Open Source? (Yes)
This seems like software that would be useful to just about anyone in the workforce that works on a computer.