I already posted a link to this site in another thread, but I think it would be good to give it a thread of its own.
This is a Dutch site, but this is a direct link to the English version of the VoteMatch. This is how it works:
Vote Match USA tests your political preference based on the positions of and statements made by the two presidential candidates, John McCain and Barack Obama.
For both candidates, we have chosen issues on which their positions differ significantly. Two statements will appear on the screen each time, and you choose the one you agree with most.
After reacting to all statements, you will see the positions you support on the screen. You can indicate which standpoints you consider to be especially important. These will then count more heavily in the final results.
On the results screen, you will see the candidate whose views most reflect your own.
You can compare yourself to both candidates and click to see the scores on the individual issues. You can also check how other Vote Match users made out and which issues are extra important in determining the results.
Maybe it would be cool if everyone could post their scores... Mine was 97% Obama, 3% McCain.