[Quiet Man Cometh]

I've seen Goodreads around and have used it to look up reviews when I was going through my mother's book collection. I wasn't too interested in making an account because I've never really wanted to bother making a log of the books I've read. I've picked up LibraryThing because it has some professional application and because I actually do want to start a little miniature library at some point. The books I enter are the ones that I own and would (theoretically) circulate.

One person's description was that LibraryThing puts book data ahead of the social aspect, while Goodreads does it the other way around. Another person described it as LibraryThing is a library, and Goodreads is a bookstore. Where you go depends on what your purpose is.