Advertising.com The nation's largest third-party display network, meaning it allows AOL to connect advertisers with advertising space beyond its own sites. If you were one of the 183 million Americans online in December, there's an 86% chance you saw an ad served by Advertising.com.
Adtech Expands the ad network internationally, with clients in 25 countries.
Third Screen Media Connects advertisers and publishers with mobile-phone carriers. The mobile ad market is expected to grow to $4.7 billion by 2011, from $421 million in 2006.
Tacoda Tracks specific users' Web behavior and gathers demographic, geographic, and page-view information about them. Then it uses that information to serve up highly targeted ads.
Quigo Much like Google's ubiquitous AdSense, Quigo's AdSonar scans the content of Web pages to place contextually relevant ads — automotive ads near automotive content, for instance.
Lightningcast Places streaming video and audio ads and measures their effectiveness. Also licenses its technology to other companies, like Comcast and Reuters.
A version of this article appeared in the April 2008 issue of Fast Company magazine.