As you can see in each forum, the ratings have changed. In each thread on the right side of the first post you will see a thumbs up/down. When you click this it gives the thread rating a +1/-1. If you vote thumbs up, the thread will get bumped up (and the number will reflect this). If you select thumbs down, it will get pushed down (and the number will reflect this). Everyone can vote.
We are going to try this out to see how well it works but keeping the good discussion going and the junk threads out of sight.