Given Bookwhirl's poor rep for spamming and poor English skills, that might not be a good one to associate your book with?
I've heard about Library Thing but, honestly, haven't used it. Is it any good?
Fast growing newcomer Wonderful reads of the Month . To understand how that works, read this guestpost
I've been compiling a list: disregard my color coding...
www.published.com
www.bookhitch.com
www.authorsden.com
www.slake.com
www.authortree.com
www.writers.net
www.listal.com
http://www.sharing-books.com/
http://weread.com/
www.writerscafe.org
www.discoverabook.com
www.nothingbinding.com
www.editred.com
http://reader2.com
www.goodreads.com
www.bibliophil.org
www.librarything.com
www.shelfari.com
www.booksie.com
www.xenite.org/internet_authors/announcebooks.html
www.polkadotbanner.com
www.booktour.com
http://www.freado.com/
http://www.filedby.com/
www.redroom.com
www.chainreading.com
www.gurulib.com
http://www.bookarmy.com/
www.zazieweb.fr (French site)
www.connectviabooks.com
www.shelfcentered.com
www.booktribes.com
www.bookswellread.com
www.babelio.com (French site)
www.anobii.com
www.litpitch.com
www.booklicker.com
www.jacketflap.com
www.ibookdb.net
www.shared-self-publishing.com
www.axisavenue.com
[FONT="]http://www.bookarmy.com/[/FONT]