I recently started using this great new product called RescueTime. It's a little app I run at startup that doesn't seem to slow down my computer at all but keeps track of what I do at the computer. Later, I can tag my items.
Initially I was pretty resistant to the entire tagging thing-- but you know, the idea has totally grown on me. Because I tag them instead of an automated algorithm, the numbers / tags in the software mean something real to me. I know exactly what constitutes 'work' and what doesn't.
Here's my graph for part of today (as of 2PM or so)... already about 7 hours of work, and the day is only half done. Yes! ;-)