Years ago I had something like this on my vBulletin forum, the CashMod. Members would earn virtual cash that showed up under their names for each post/reply they make, a post would earn 5 points, a reply earned 3, etc.This encourages activity on your forum.

They can spend that cash on anything in your virtual store like ad space, a pinned post, special title, highlighted name, purchases on your web site, etc. You can set the rewards to whatever you want.

Just an idea to throw out there that would be cool.