And sorry, I'm sceptical about idea of forum just for referral links. First off all, who are going to promote their affiliate links on forum with zero traffic? And I doubt that people are going to join this forum just to join websites through referral links. Ad slots, social networks or blogs is much better places to promote affiliate links.
It does work to a certain extent.
A faucet and casino sites recommendation site I have (I do promote it, albeit not aggressively) still nets me email inquiries from some site owners on listing them. As long as it's attractive and not too complex, there is some sort of enticement to get free listing.
Now speaking of it, I should resume doing so here. Almost forgot