From Wikipedia... According to one report, total sales generated through affiliate networks in 2006 was £2.16 billion in the UK alone. MarketingSherpa's research team estimated that, in 2006, affiliates worldwide earned $6.5 billion in bounty and commissions from a variety of sources in retail, personal finance, gaming and gambling, travel, telecom, education, publishing and forms of lead generation other than contextual ad networks such as Google AdSense.