I have noticed a problem in the forums where there will be multiple topics created about the same thing. For example, there were something like 4 topics created, on the same day, about a petition on whitehouse.gov. I don't mind if a topic is repeated a few days later, but it is annoying when half the page of topics are all about the same thing and were all created on the same day.
I don't know of any way to fix this problem. One idea is to allow up/down voting on forum topics. Another idea I had was to have an option for users to flag a topic for an administrator to review the topic, and if it is a repeat, it could be deleted.