I've been through this scenario a couple of times myself... It never fails with lending my books out and about a couple of months later, when the semester is done and they should be returning it, that's when all of the sudden the person says, "Oh! I lent it to someone else".
As far as money is concerned, depending on how much they ask, I just let them keep it cause I know I'm not getting it back. If it's a big amount, I say "I DON"T HAVE IT!"
