One of the features that makes our ASP.NET forum software different from the others is the built-in rating system and a feature that hides unrated posts from viewing.
Every registered user can vote a message "up" or "down" by pressing the "thumbs up" or "thumbs down" icons next to it. Every topic has a "show rated posts only" link that hides unrated answers and shows rated posts only, sorted by their rating (top-rated messages first). This handy feature makes finding useful posts really easy, filtering all the "noise", when searching for answers.
Rating a message also adds (or subtracts) points to the author's "reputation" that is shown on his profile page.