I belong to a couple of groups that you can swap books back and forth for free! Well not exactly free. The books cost nothing you only have to pay shipping when someone requests a book from you. When you request a book from someone else they send it to you for free. You earn points by sending books out and by inviting others into the club.
Here is an excerpt from the invite letter:
Do you have any used paperback books lying around? I did, and I finally found a great way to share them with other people.
Let me tell you how it works because it is so easy. I listed a bunch of books on the site (you have to list at least 10 books to get in the club) and I got 2 free book credits to get me started. So you can order 2 books right away – free of charge and have them mailed directly to you. No strings attached. No gimmicks. No spam mail. Nothing! You just have to love reading.
Then when another member selects one of my books that I have listed, I mail it to them. Yes, I pay for the postage. But then I get a book credit and I can select a book that I want. So another Club Member returns the favor and mails me one of their books free of charge. For every book I mail out, I get another book in return – a true shared system! And if you do sign up, please list my email in the referral section because then I get another free book.
To check it out click on the link in my sidebar for Paperback Swap.