There are also products that are designed to work in concert with Adsense. The company I work for, Adroll.com, enables publishers to use Adsense as back fill,

There are also products that are designed to work in concert with Adsense. The company I work for, Adroll.com, enables publishers to use Adsense as back fill, set a reserve eCPM, and earn premium CPMs by banding together with other similar publishers. I hope this is helpful.