Sales generated for e-commerce businesses by U.K. affiliates in 2005 are expected to double year over year - the second year in a row - and account for 1.1-1.35 billion pounds in sales for merchant partners in 2005, up from around 600 million pounds in 2004, according to a new E-consultancy report titled Affiliate Marketing Networks - A Buyer's Guide. That growth surpasses the rates for both online advertising and search engine optimisation, which E-consultancy expects to grow by 32 percent and 70 percent respectively.

"Affiliate marketing is becoming a real no-brainer for many businesses looking to drive online sales while avoiding the usual risks associated with online and offline marketing," according to E-consultancy CEO Ashley Friedlein, because affiliates "are themselves becoming increasing savvy as internet marketers."

Among key affiliate marketing trends identified in the report: Financial services, gambling, telecom, entertainment, travel and consumer electronics are sectors with strong growth rates; affiliate marketing remains largely consumer-focused; affiliate marketing is outsourced to agencies by 15 percent of merchants; and affiliate networks expect consolidation within the next few months.