I'm enjoying my latest obsession so much, I feel compelled to share it. Do you have a bunch of books that you no longer want? Trade 'em! On Paperback Swap (www.paperbackswap.com) you can list books you don't want anymore. When someone wants your book, you mail it to them (you pay the postage, but you can buy postage through the Web site with Paypal, and you can print postage-paid wrappers or labels). When the person on the other end receives the book (or when you mark the book mailed, if you used the pre-paid postage option), you get a credit. You can then "shop" the approximately 4 million books listed and choose your book! The sender pays your postage. List 10 books that you want to get rid of, and you will get 2 free credits which you can use immediately.
For someone like me who reads a lot, but only likes keeping "special" books on my shelves, this is a great way to feed my addiction. Check it out, and if you sign up, write my name in the section where it asked how you found out about it. I'll get a credit for referring you. Can't beat that!