North American search engine marketing spending totaled $9.40 billion in 2006.
Paid search accounted for 86% of spending; SEO 12%; paid inclusion 1%.
Source: Search Engine Marketing Professional Organization, BtoB, Feb. 28, 2007
U.S. search market share (Feb. 2007)
Ask Network 5.0%
Time Warner Network 4.9%
Source: comScore Networks
They said it
"The average advertiser isn't going to know about the server click farms, or the ruthless people who are hiring people to click you out of the top spots. If you're bidding on higher-priced keywords, the bigger the chances that you're getting invalid clicks and don't even know it." —Michael Caruso, co-founder and CEO of ClickFacts
Source: BtoB, Feb. 12, 2007