NuRatings is a system that enhances your vBulletin community by adding 'digg-like' rating functionality.
Users can rate other users, posts and threads by clicking on 'thumbs up/down' buttons next to each thread or post.

You can then show the top rated threads or users in your forum home page (or anywhere else). Users also have the ability of filtering the posts and threads they want to see based on their net rating.

Link

*Bump*

Need this myself !