As you all might know, forum is very hard to monetize, because people usually visit regularly. Regular visitor has low CTR, because them know where the ads are and tend to ignore it. But there are ways to overcome this:
- Sell banner space. You can place the banner at the top, left, or right of your forum. You can offer the space for people who are participating in the forum. The revenue from selling banner space depends on how much traffic you have.
- Use Adbrite, they works great in forums. Adbrite works on high traffic website, like forum, humor, and games.
- Charge fee for exclusive member area. You can share your knowledge at this special member area. If you can provide them with helpful information, monthly subscription will last long.
- Accept Paypal donation.