After a few days wandering around "literary" social-networking sites, I'm feeling a bit frustrated by how people interpret their participation in a very solipsistic way. Listing your own books is half the fun, I get it, but certainly the other half is hooking up with other like-minded bookworm geeks; you should put in a little effort to make your shelf accessible to them. Why then few can be bothered to tag their books? Without tags, I'm left to dig through hundreds of items I don't care about, whereas even a little classification (like separating novels and non-fiction, or fantasy and contemporary) would go a long way to help me define that you like the same sort of harrypotterish works I (might or might not) enjoy.
So please, if you are serious about this sort of sites, try to tag your books, even a little bit. Splitting your shelf in groups containing less than 100 items would already be enough, especially if your collection contains 200+ editions of books blatantly plagiarizing JRR Tolkien.