Are you one of those people with tons of books all over your house? I've discovered a great way to get rid of some of my old books and stock my classroom library all at the same time.
It's called PaperBack Swap and it's very easy to use. It's free to join. All you have to do is put your unwanted books up on the site. If someone wants a book you have, you get notified and you send it out to them. When they indicate that they got the book, you get a credit to get a book from anyone else on the site. The only cost to you is the postage for sending out your own books, which runs between $2-$2.50 each. The books you get are yours to keep.
If you want instant gratification, you can also purchase credits for $3.45 each. There is no shipping charge. This makes PBS the cheapest place to get books on the web. (Even a 1-cent used book on Amazon still carries a $3.99 shipping charge.)
PaperBack Swap also has a sister site where you can trade CD's. I believe the credits between the two sites are interchangeable.
You'll love this, trust me! I've gotten tons of books so far, and cleaned out a lot of dusty old ones in the process. Unlike giving them to charity, with this system you know each book is going to someone who genuinely wants it. If you live in an area that lacks a decent library or used bookstore, PaperBack Swap could be one solution. Try it!