TWO TOOLS FOR READERS

Fiction DB calls itself "the essential fiction reference." I don't know about that, but it is a neat resource. You can search for book titles by author (including pseudonyms), series, genre, or keyword. There are reviews, links to author websites, and the ability to find a vendor for the book (or sell your book on your own). There's even a wish list. You can upgrade (for US$29.99/year) and get a free book and access to some other (non-essential) services. The site is updated monthly.
Looks useful.

URL: http://www.fictiondb.com/

PaperBackSwap allows its over 1300 members to swap books (not limited to paperbacks) easily. You list your books (you get 2 free credits with the first 10 you list), then exchange them with others (1 credit=1 exchange). A neat feature: you can print out postage from their site and not have to go to the post office. I haven't used it (yet), but it seems easy and is free.

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