It might be a good idea. If for nothing else, to keep the main board more on track. I definitely think there should be some ground rules though, as far as spammers and one time posters and stuff. People who only use websites for repeatedly posting things that they're trying to sell and don't contribute anywhere else on the website kind of annoy me, but that might just be me. I would be all for a rule of something like a 20 post minumum to post in the classifieds board or something. That would encourage posting info regarding fishing, in order to use the classified board, rather than just a way for somebody to make money without contributing to the site. JMO.
-Brian