Quirkology by Richard Wiseman (it turns out there are two editions, either is fine)
If..., If... Volume 2, and If... Volume 3, by Evelyn McFarlane and James Saywell
Freakonomics by Steven D. Levitt and Stephen J. Dubner
Mistakes Were Made, but Not by Me by Carol Tavris
Navelgazers Dictionary by Charles Hodgson
Brainiac by Ken Jennings
Why We Suck by Denis Leary
Myths, Lies and Downright Stupidity by John Stossel
Spoiled Rotten America by Larry Miller
He Talk Like a White Boy by Joseph C. Phillips
Also, anything from thinkgeek.com, especially books or T-shirts, or T-shirts from mentalfloss.com would also be super-groovy.
And don't worry, just because I'm using this space to promote my own personal agenda does not mean this is turning into a blog...I refer you to the name of this page as evidence.
