Winner is a complete science fiction book club with original series of books and all-new short fiction. One can get all information on science fiction and fantasy books with their authors, cover art, ratings, bibliographies and commentaries.
Librarything allows you to catalogue your books, using amazon searches, the Libary of Congress or other world libaries. Review, and rate these, and share with friends. Import from anywhere. Tag, list by book cover or lists, there are large discussion groups also, an early reviewers club, and LibraryThing widgets to share your book collection in various ways on your blog. Free accounts allow for 200 books. Over this, a small subscription yearly or a lifetime membership is available.
At Winner one can Find Science Fiction Fantasy books from Winner Trilogy an online book store, offering information on new releases, old favorites and forthcoming Science Fiction.
Bookcrossing has a unique way of sharing books - it's users leave their old books on park benches, coffee shops etc. But the site itself also offers a community to discuss books, authors and characters.
Bookcrossing - share books via this famous community - register the book, and leave it to be picked up locally at a park, coffee shop or anywhere you purposely leave it. You can also hold a library of books read onsite for yourself.