Over at 43 Folders, Merlin Mann mentioned the "Sullivan nod," which, according to Wikipedia, is a "sales technique used to create a subconscious suggestion to a customer to purchase one particular item out of a list of like items."
A Sullivan nod is executed by nodding slightly, by approximately 10–15 degrees, when the item it is hoped the customer will choose is reached. The key is to make the nod perceptible, yet subtle, so as to not distract. The nod is best done with lists less than 5 items in length. Studies have concluded that 60–70% of the time, a Sullivan nod will result in the customer choosing the 'recommended' item.
Mark Frauenfelder is the founder of Boing Boing and the editor-in-chief of MAKE and Cool Tools. Twitter: @frauenfelder. Come and hear Mark speak at the ALA conference in Chicago on July 1.