The folks over at American Progress have an Interactive Quiz: How Progressive Are You?. The quiz consists of 40 questions which you either agree or disagree with on a 10 point scale.
My final "ideological score" was 297/400, which makes me "very progressive." The average score, according to American Progress, is 209.5, with Obama voters averaging 244 and McCain voters at 169.
So, just in case you hadn't noticed from the previous 1,100 or so posts here: I lean slightly to the left. As if we needed this quiz for proof.