It's a library thing

Librarything.com allows you to catalogue your personal library with user-defined "tags" such as "beach read", "magical realism" or "stolen from Reid Kerr College". You may keep your catalogue private or let others see it, and you can search other's catalogs. Includes lists of top books and authors, and a blog. Free for up to 200 titles; there is a fee for unlimited use.
Just a thought.