I just finished my library for Library Thing (I'll share my thoughts soon). I do like Library Thing because I can see who else owns the books I own, do my own reviews and post them to Twitter and join groups with unusual names like "Librarians Who Library Thing", "Awful Lit." and "Tea!" . But the number of books you can catalog for free is limited to 200. Does any librarian own less than 200 books? Possibly. It doesn't cost much to upgrade to an unlimited library and it's good for book swaps and insurance purposes. The only thing, I wouldn't include books I don't own on Library Thing, which is why I like Shefari.
Shefari is a social networking book site, like Library Thing. You let people know what you read, what you are reading and what you're going to read if you choose. You can choose your display shelf and just add books. You can also catalog magazines and individual comics (which is harder to do with Library Thing). I liked having a separate place to review and recommend books I read from my school library and books I checked out from the public library without taking up my Library Thing space. I also have two separate bookshelves: one for my young adult and adult reads and ones for children's books and professional books. Check it out. Create a shelf for books not in your personal library and share. I'm always looking for books to read. Hopefully you'll try out some of the books on my shelves.
My Children's/Professional Shelf:
Queen B's Children's Books
My YA/Adult Shelf:
Until then, keep reading!