I like the idea. I think there should be a skip button as there are a couple sites that I wasn't able to review properly (one specifically asked for people to review it in another language and the other required me to sign in). I also think it'd be cool if the homepage showcased some of the highest rated sites, like the way Logopond ( http://logopond.com/ ) works for logos.
If the creator of FeedbackRoulette is reading, skip button pronto!