Most forums focus on a niche, making a forum/website an ideal candidate for creating a niche directory. Instead of creating a general directory, you can cash on the new craze in the directory world; bid for position directories.
I created a free bidding directory script that can help you start your own bidding directory, its called Link Bid Script or LBS for short. You can find out more about LBS here and you can download LBS at my webmaster forum.
Good luck should you decide to start a bidding directory