Casale Media have emerged as a top network, offering great rates for leaderboards, skyscrapers and pop-unders, and paying 70% of the revenue with a minimum payout of $25, they are hard to beat.
Size: Skyscraper [120x600]
Conversant (formerly ValueClick Media) currently represent the pick of the independent online ad networks due to their great support and service, as well as decent payouts.
Google is the leader in search technology on the internet, and their AdSense Network offers accurately targeted text adverts targeted to the actual content of each page, therefore being able to offer high eCPMs.
Tribal Fusion have emerged as one of the leaders in internet advertising by only representing high quality sites with original content, and so are very difficult to be accepted by, although they do offer the highest paying campaigns and a great service.