The _SAS Survival Guide_ is pretty good. I keep the Collins Gem edition in each of our BOBs.
I think my favorite for people just getting started is _98.6 Degrees: The Art of Keeping Your Ass Alive_ by Cody Lundin.
A good one for starting to understand survival psychology is _Deep Survival: Who Lives, Who Dies, and Why_ by Laurence Gonzales. If you're only going to buy three books, it should probably be those three.
Doug apparently agrees with me (
http://www.equipped.org/books.htm) which is no surprise, since I bought those three and pick my next survival library recommendations from that page.