I don't remember who told me about PaperBackSwap.com but I adore you! I have been a member for a couple months and have been swapping like a fiend. I put up a lot of my Star Trek Books because I won't be reading them again (minus Peter David) and wanted to be rid of them. I've posted other books. I've gotten books. I've posted the books I've gotten and read. It is like the library only you are paying the postage. The thing is if I get a book I must keep... it costs me about $2.13! I love that. You get credits for every book you swap which is like a free book but really not because you paid the $2.13 to ship a book to someone. If you want a book and have no credits you can buy one for $3.45. It is so simple and that make books cheaper than used bookstores.
And they even have SwapCD.com which is the same thing only with your CDs. I mean who doesn't have a ton of CDs you want rid of. I mean I do. I can post them their and swap to get something I really want! I love it.