OtherThing(s)
LibraryThing is not the only tool for putting your books online. Others include:
Delicious Library (for the Mac)
These sites are primarily focused on sharing reading lists and general social networking around books. So if you're looking for someone else who's read your favorite book, any of them might be of interest.
But if you're looking for that vicarious-librarian thrill, Thing is what you want.