I promised to post again after receiving some books - so here it is.
I read somewhere about PaperbackSwap.com (if you join, please use this link). It is a site that facilitates the trading of books. Simply list at least 10 books that you are willing to trade. People request those books and you send them the books (you pay the postage). In return you get credits that allow you to request books from others. They even give a couple free credits for signing up.
As I began sending out books, I was nervous. I used their online system for purchasing and printing postage. By doing this, I got my credits instantly. I sent my books out and soon got notification that they had arrived.
I've requested several books and received many already. I've enjoyed reading the books and always love getting packages in the mail. I also joined the companion site SwapaDVD.com. I have had excellent results with both sites. I received all the things I requested and everything I sent was received.