Don't forget to pick up "How to lie with statistics" while you're at it; nobody should be allowed to listen to statistics without having read it at least once.
Oh, I didn't want to encourage people to start using the tricks in there to start flamewars on this list... ;-) I'd rather people at least *tried* to behave properly with the data. Huff's book is very good, though, and well worth a read if you have to rely on numbers in things you read, or you want to see the stunts the newspapers pull. The scary thing is, not all of them are deliberate. Sometimes they really are that clueless.