ValueClick Media is the resulting network of the acquisition of Fastclick by Valueclick in late 2005. This new combined network combines the best part of Fastclick, namely their impressive publisher interface and statistics, and Valueclick, which was their large international media selling team.
Burst Media are one of the longest established online advertising network, being established in 1995, and have survived due to their high quality network of publishers and advertisers, and the great targeted ad buys which they are able to get for independent sites.
CPX Interactive have emerged as a great second tier network due to offering all the popular creatives with decent payouts, great support, and 100% sellout rates.
RealTechNetwork is a relatively new advertising network, but is establishing a reputation as reliable and providing decent rates, especially from US/Canada/UK.
BannerConnect are a well established Netherlands-based ad network that offer good fill rates across all countries