Originally posted by Ryos
From the board's faq:
How do I rate a thread?
You may find a small menu on thread pages which allows you to 'rate this thread' with a number between 1-5.
Casting a vote for threads you view is entirely optional, but if you think that the thread is superb, you might rate it as a 5-star thread, or if you think that it's unspeakably dismal, you might choose to rate the thread with a single star.
Once enough votes have been cast for the thread rating, you may see a set of stars appear with the title of the thread in the thread listings. These stars reflect the average vote cast, and can allow you to quickly see which threads are worth reading if you are on a very busy board with a lot of threads.
I don't think you can search for threads based on ratings, and I've yet to see a thread with enough votes to be rated.