I just joined the rubicon project, and it's pretty interesting. Basically, they do ads for you, but they compare the statistics for each page, and pick what ad company they will run ads from. So if you have a page that does good with auction ads, they'll run that ad... if you have a page (read: most ;-p) that does good with adsense, they'll run adsense. It's ... brilliant really. Check it out:
www.RubiconProject.com

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