The computer equivalent of a taxi cab fare meter. Clocks your time, what you've been working on and adds up how much $ you should charge clients. http://projecttimer.sf.net/
All the project timers I've seen use much memory. This one, with 17MB, is not an exception. However it gives me all that I need and is fast, so I'll stick to it. After all I got a new machine with some ram this year :)
I like the way it follows your tasks, and lists them comprehensively - I am a little perturbed at the number of projects that get generated, it seems I really flick from one to the other. It's almost terrifying how big a pile of activities builds up when browsing on the web researching. Very illuminating of where my time goes.