The way I see it, is the more people that use Yedda, the more ads will be clicked on.

The key is community, perhaps members can make money as they answer questions...maybe one dollar every 5 questions answered.

But this would be gamed, because I could have two user spaces, and just ask myself basic questions all day long.

Maybe you only make money on questions you have been invited to answer, but still if I game it enough, I will be invited to answer questions I ask from another user space. 

Anyway the key is to generate membership, perhaps Yedda can market themselves to listservs, these places have lots of members and experts.