Affiliate marketing programs are commonly used by large and small companies as a low-risk means of obtaining new customers. However, some affiliate marketers have been plaguing search engine marketers for years. Google will serve only one ad per display URL, and the display URL must match the destination. So what happens when affiliate marketers pick up your offer and start using search to drive acquisition for you? (This article first appeared in the June 2007 edition of the Essential Guide to Search Engine Marketing.)