I've noticed that there are buy/sell/trade sections on forums all over the place, but none that encompass all together.

There is one now, called Buy and Sell Gigs which is specifically meant for Internet Marketers, SEO's, website designers, domain sellers, etc.

The $5 and $10 gigs don't have any commission through July, 2011, so the seller keeps all of the earnings.

There's a section for Warrior Forum too, so people can list their jobs in more than one place....