10 Websites for Book Lovers..from iLibrarian

You might also want to checkout http://openlibrary.org.
Open Library has a catalog of 23 million books with 1 million books
having full-text for online reading.
It also has an open book cover repository with more than 5 million book covers.

There are APIs for accessing all the available information.

http://openlibrary.org/dev/docs/api
http://openlibrary.org/dev/docs/api/cover

10 Websites for Book Lovers
>
> At this point most everyone has heard of LibraryThing, the most popular
> social cataloging website online, and perhaps even of the Amazon-owned
> Shelfari, but here are a few websites for book lovers that you may not have
> heard about:
>
> BookSprouts
>
> BookSprouts is a website where you can join and create book clubs. Members
> can vote on which book to read next, have book discussions in forums, post
> book reviews, and hold meetings.
>
> Blippr
>
> Blippr is a website where you can add short reviews of 160 characters or
> less of books, movies, music, games, and applications. You can connect your
> account to many other social networks such as Twitter and Facebook where you
> can continue your conversations.
>
> 22 Books
>
> 22books will allow you to quickly create book lists of any type. You can
> make comments on books in your list, and embed your lists in other websites.
>
> Book Cover Archive
>
> The Book Cover Archive is a collection of over 1,000 book covers categorized
> and browsable by designers, authors, titles, art directors, photographers,
> illustrators, and more. Readers can leave comments on covers and can suggest
> entries.
>
> BookJetty
>
> BookJetty is a social cataloging app that will let you set up a bookshelf of
> titles you own or want and then easily search for them in your local library
> with a click. Amazon and other booklists can be imported for quick startup.
>
> Book Glutton
>
> BookGlutton is a social community where you can read public domain books and
> discuss them with groups. Members can annotate books and make their comments
> public for discussions or keep them private. You can even upload your own
> books.
>
> Gurulib
>
> Gurulib is a social cataloging program which lets members organize their
> book, movie, music, game, and software collections. The site allows members
> to use their webcams as barcode readers to scan in items. Items be loaned
> out and members can track borrowed titles.
>
> Listal
>
> This social cataloging website enables members to catalog books, movies, TV
> shows, video games, DVDs, and music. Members can loan their items, import
> and export their catalogs, and create favorite lists that others can comment
> on.
>
> GoodReads
>
> GoodReads is a robust social cataloging site in which members can create
> lists, write reviews, form groups, create trivia questions about titles, and
> converse in forums.
>
> Paperback Swap
>
> PaperBack Swap is a community hub for trading your paperbacks, hardbacks,
> audiobooks, and textbooks with others. Members can easily mail books as the
> site provides exact postage labels which can be printed out. Once a book is
> mailed, you can request one for yourself from the cache of over 3 million
> titles available.