I know a lot of regulars on this blog are thinking they match best with Obama, but you might be surprised.
This quiz does a pretty good job of explaining the issues so you can take a firm stance one way or another, and based off my results (Biden and Hillary tied for my top match, Obama a little further down the list), I'd say it's pretty accurate too. It scores you on your percent compatability with a candidate (or Joe and Hillary to get some Democrat diversity) on social issues and economic issues. I think voters would really benefit from something quick and painless like this.
But the benefit's yours now--it's a nice little way to kill some time on a Friday afternoon when you're waiting to get back to the CW.