In addition to the one above, that is a sister site of this one..
http://www.webaffiliatecreators.com/forum is mine
http://forums.digitalpoint.com/ is a huge webmaster site, not so much an affiliate site, but you can buy and sell links there, it’s probably the biggest available.
http://www.sitepoint.com is another, much like digital point, but it costs money to advertise there whether buying or selling
Dani Web (search google for the addy) is another big one.
All of those are more webmaster sites than affiliate sites.. but i think theyre what you’re lookin’ for 
~LadyH