This thread is for books you read you believe everyone should read.
My first suggestion is for The Art of Deception by Kevin Mitnick.
Mitnick is a social engineer who penetrated the security of the biggest companies, copied the source code of many big programs and similar feats. He was condemned by the court with an exagerated sentence (they counted the stuff he copied as being "lost" by the companies who hosted it, Mitnick did no actual damage). All of this was accomplished through social engineering (manipulating people in doing what you want, giving you passwords, etc.).
He now runs a consulting company to train people to resist attacks such as the ones he was performing and that's the goal of the book too. It's full of credible real-life example that most people would fall for, followed by an analysis on the attack and how to prevent it.
It's really an eye opening book and I highly suggest it to everybody.