Bought one myself a while back after it caught my curious eye in a local store. A good portion of the book is hazardous materials info... which can actually be downloaded for free from:

http://hazmat.dot.gov/gydebook.htm

A lot of the information you'll probably never use unless you're in law enforcement/fire/EMS. There is some other information contained, though... stuff like basic medical techniques, math formulas, weather information, morse code, etc.

It's worth the $10 just for the "wow, how did they print so much in such a little book" factor. <img src="images/graemlins/grin.gif" alt="" />