A new kind of advertising company has arisen in the last couple of years.

These companies are built on the proposition that webmasters are not managing their ad inventories as profitably as possible. This is probably true.

These companies are trying to wedge themselves between publishers and ad networks, and they are making some headway.

Here are a few of these firms:

You sign up with these systems and they choose which ads to display on your site based upon how much each ad network will pay for the impression.

Rubicon has an AdSense account of their own and all Rubicon publishers use that account. PubMatic and YieldBuild both use your AdSense account directly.

The goal for these companies is to make enough addition revenue from the ad networks to be able to split that additional revenue with the publishers and still have enough revenue left over to turn a profit. There's no telling yet whether this business model will succeed.