I just found a great site: Bibliophil.org. It allows you to catalogue your books, review them, sharing your library with others (to view), and connect with other users to build an online community of book lovers. It's really cool. And the coolest thing is that it's free -- they do appreciate donations and I think it's worth it. You can see each other's libraries and get to learn more about books you've never heard of... So great!
My user ID is maestrowork. Once you register, we should add each other to our buddy list. Also, don't forget to add my book to your wishlist :) (the ISBN is 1-933016-32-9).
Happy reading and sharing!