A few of mine:
Influence - Robert Cialdini
Describes simple techniques that can greatly influence people’s behavior. Understanding these brings awareness to how people are trying to manipulate you.
Art of Invisibility - Kevin Mitnick
Describes how hard it is to be truly anonymous today and how easy it is to track people. I think everyone deserves to know how much they are being spied on.
The Demon-Haunted World by Ann Druyan and Carl Sagan
Flim-Flam! by James Randi
Both for the same reason, they both taught me more about critical thinking and skepticism, then I ever learned in all my years in school.