Robert Cialdini's Influence is a good read. Cialdini emphasizes influencing people by using behavioral reflexes (like reciprocity, recognizing authority etc.) and how to defend oneself against it.

Then, some of the pop-psy books on irrationality give good insights - I particularly liked Dan Ariely's writings, and Chabris/Simons' The Invisible Gorilla -- but of course they are primarily about pointing out bugs in our mental wetware rather than 'hacking' it.

Anyhow, beware Sturgeon's Law.