If you want to exchange, catalog, or sell your books online, the following sites may help you to get started.

http://www.paperbackswap.com/index.php

http://www.chancexchange.com/

http://www.swaptree.com/

http://bookmooch.com/

http://bookins.com/

http://www.readitswapit.co.uk/TheLibrary.aspx

http://www.frugalreader.com/index.php

http://www.whatsonmybookshelf.com/

http://www.swapsimple.com/index.jsp

http://www.titletrader.com/faqs.php

http://www.bookhopper.co.uk/

http://www.comicbookswap.com/oscommerce/

http://www.swap-bot.com/swap/show/14549

http://labnol.blogspot.com/2006/02/online-book-swap-websites-for.html