The Gift of Fear by Gavin De Becker
Gavin de Becker has done a bunch of security work for high level politicians and has worked for the CIA, this book is about how our first instincts in situations that make us feel fear or apprehension are usually correct, and how we can pick up on subtle behaviors people make in order to accurately predict their intentions. Interesting and worth a read for sure.
I'm a big fan of all things non-fiction (don't mind fiction, but books that are fiction are no longer high on my list) mainly because you could learn a lot from such books.