http://yodel.yahoo.com/2007/09/04/yahoo-to-acquire-bluelithium/

[...]Advertisers seek essentially three different outcomes when they buy display (or graphical) ads online — either to build brand awareness, promote something new, or drive some kind of transaction (a lead, a sale, a new customer). The latter, known as performance marketing, has been exploding online over the past year because it’s typically served around social media content, where there’s no shortage of inventory.[...]

[Moved from "Yahoo! is acquiring BlueLithium" – Tony]

<< Yahoo! just entered an agreement to acquire BlueLithium, one of the largest and fastest growing online global ad networks with a stable of direct response products and tools for advertisers and publishers. BlueLithium runs the fifth largest ad network in the U.S. and the second largest in the U.K., providing access to valuable audiences and increasing our ability to sell performance-based campaigns both on and off our network. >>

http://yodel.yahoo.com/2007/09/04/yahoo-to-acquire-bluelithium/

Should be interesting to see what Google and Yahoo! do next year after their ad network acquisitions have been integrated.