LibraryThing!

Was a little skeptical about the whole thing at first but I actually thought that it was really quite neat. Needless to say I don't necessarily own all of these books, but picked some of my favorite books. It is really cool to see how those books rank and what other people say about them. One of my favorite books only 15 other people own, which is a shame because it is a really funny book. But there are all kinds of things you can also do on this site.