Do you have the need to track your time across different projects? Maybe you're billing for consulting hours or just trying to keep track of how much time you spend on email vs. coding vs. meetings. There are a zillion timer apps out there that all suck. I finally found one I like: Slimtimer.
My only complaint is it's a bit geeky. Everything is tracked down to the seconds. And getting a simple time sheet involves the words "Pivot" and "Rows" and "Columns". But it's still all very usable, and in general the application is very well executed. Recommended.