Paperbackswap.com
Ooh, I’m having such a fun time shopping for new books and getting rid of the old twaddle and 
books that were given to me by my MIL (In her defense, I don’t think she believes them anymore either…)
So it works like this… you sign up and list 9 books. They give you 3 credits just for listing. After that, each time you mail a book to someone, you get 1 credit. 1 credit buys you 1 more book. The shipper pays the shipping costs and when you order a book you get it for completely free. To ship it you print out the book wrapper on your printer, and that includes the mailing label, so you don’t have to buy an envelope or anything. It tells you how much postage to put on there, so you just slap it on, throw it in the mailbox, and voila!
Out of my listed books, 5 have been requested, so I’m well on my way 
Plus I’m having fun filling up my wishlist 