Anyone know of good places that allow you to sell AD space?

Tweet

So I saw a place called sitepoint and i'm looking for other sites like it that allow me to tell the amount of traffic I get to my site & to get potential people willing to pay to buy AD space on my site. Anyone know of any good sites? Preferably one's focusing more around paying by Paypal then paying by check? I'm looking because although Adsense is fairly well-paying i'm going to be wanting to look for a bit more of a stable payment to add on top of Adsense. Please don't suggest places that Google Adsense isn't OK with as Adsense stuff will be on the site. Thanks in advance!