One of the largest book communities online is Library Thing. Library Thing is the place to catalog your books online. Thirty million books have been cataloged. “Library Thing is an online service to help people catalog their books easily. You can access your catalog from anywhere—even on your mobile phone. Because everyone catalogs together, Library Thing also connects people with the same books, comes up with suggestions for what to read next, and so forth.”
Library Thing is a full-powered cataloging application, searching the Library of Congress, all five national Amazon sites, and more than 80 world libraries. You can edit your information, search and sort it, “tag” books with your own subjects, or use the Library of Congress and Dewey systems to organize your collection.
“If you want it, Library Thing is also an amazing social space, often described as “My Space for books” or “Facebook for books.” You can check out other people’s libraries, see who has the most similar library to yours, swap reading suggestions and so forth. Library Thing also makes book recommendations based on the collective intelligence of the other libraries.”
Some of the groups on Library Thing are librarians (5580 members); science fiction fans (2786 members); what are you reading now? (2495 members); fantasy fans (1935 members); crime, thriller and mystery (1562 members); writer-readers (1384 members); non-fiction readers (1349 members); and 1010 books to read before you die (1064 members).