Voting pluggin for comments

Hello,
Is there a pluggin that would allow visitors to a blog to vote on the comments and then have the comments automagically order themselves.
What I would like to do is allow visitors to read a blog entry and then comment on the entry. At the same time I’d like them to be able to vote on which comment they think is the best and then have the comments automogaically re-order themselves so that they list in order of best voted comment to worst voted comment.
I’ve looked through the net all morning and while I found some good voting pluggins they were all for voting on blog posts but not on blog comments.
Is there anything out there?
mohoohoo