http://www.moderninsider.com/article54.html
I hope you didn't have a rule against unique links.. haven't been here in a while, so... yeah. But this can be a nice way to get more people to the forums, meaning more people to click ads and such..
All I can say is that it works at the forum I'm spending most of my online time..
(I picked up a few things when becoming a moderator on another forum :P )