CPC

An ad network owned by Microsoft. Their inventory is purchased upfront. They sell their inventory on a CPM, CPC or CPA basis but if it's on a CPA, their policy is to not allow geotargeting.

One of the largest ad networks in the world. Like other large ad networks, they can run media on a CPM, CPC or CPA but since it all runs on the same network, if you do a performance deal with them, volume can fluctuate significantly.

One of the largest ad networks with 13,500 sites for display advertising. They do a revenue sharing model where they share 50% with their publishers. Like other large ad networks, they can run media on a CPM, CPC or CPA but since it all runs on the same network, if you do a performance deal with them, volume can fluctuate significantly.

They also do lead generation using a co-registration program. They have a separate network for this, comprised of 1,500 sites.

An ad network comprised on Yahoo sites, the former Blue Lithium's sites and the former Right Media's sites. Their value prop is a dynamic CPM tied to a CPA goal and a real-time optimization system.

The biggest ad network in the world, which also includes AOL. Like other large ad networks, they can run media on a CPM, CPC or CPA but since it all runs on the same network, if you do a performance deal with them, volume can fluctuate significantly.