StackAdapt - Native advertising demand side platform.

Google Ad Manager - Grow revenue wherever your users are with an integrated ad management platform that surfaces insights for smarter business decisions.

Zemanta - Zemanta is an online content and links suggesting platform that provides a plugin to the bloggers, publishers and other types of content creators.

Broadstreet Ads - Broadstreet is the premier ad management platform for news publishers, trade magazines, radio...

Reddit - Reddit gives you the best of the internet in one place. Get a constantly updating feed of breaking news, fun stories, pics, memes, and videos just for you.

OpenX - Ad technology platform available as a hosted service or as an open source download.