Online Book Sharing Sites

Goodreads
Goodreads is the world’s largest site for readers and book recommendations. Their mission is to help people find and share books they love.  You can browse without logging in, or set up a free account to record and review your books. Goodreads is owned by Amazon.

Library Thing
LibraryThing is an online service to help people keep a record of their books. Create an account to rate and review books and connect with a community of readers. LibraryThing is owned by Abe Books/Amazon.