I don't like when I'm forced to write: "08:00-11:00, XX:ed, YY:ed and ZZ:ed" - that's not really informative, i.e., how much time did I spent on XX, compared to YY? But it's not the logging problem in itself that I have problems with, it's that I know that it's bad for productivity to multitask, but still I do it. Without knowing it as well, it seems. Constantly context switching is bad for productivity. So, I should only focus on one task simultaneously to make tomorrow morning a good start at the day.
Look, if you're using GTD (a nice time management methodology), but instead of doing something useful instead read LifeHacker (a nice site/blog) every 10th minute, something is utterly wrong! Not really getting things done, are you? Though, it can be hard to see for yourself. TimeSnapper lets you visualize your behaviour at the computer, putting your (potentially) multi-tasking in an embarrasingly bright light to yourself.
Thanks to Scott Hanselman for making the tools list where I found TimeSnapper.
As a side note, I really like 43folders' new direction. Or, at least, this particular post.