If you're an American and facing the 2008 election, this website may be very helpful.
Quiz to Find Your Candidate What I especially like is that each issue has a hyperlink to a page with greater detail about that issue, including a "dictionary" of key terms that get batted around by the media without any really good explanations.
I'm not telling who turned out to be the best fit for me, but it was quite interesting. I think I'll look more into this guy (oooh, there's ONE clue). I don't how objective that website is, but it's a place to start.