Influence: The Psychology of Persuasion Amazon.com Review
Arguably the best book ever on what is increasingly becoming the science of persuasion. Whether you're a mere consumer or someone weaving the web of persuasion to urge others to buy or vote for your product, this is an essential book for understanding the psychological foundations of marketing. Recommended.

Journal of Social and Clinical Psychology
The materials in Cialdini's Influence is a proverbial gold mine.