A social reading site.
I like the GoodReads site, but I didn't actually like that my Twitter status was automatically updated when I added a book to my "to read" list. I wish there was a feature so I could sometimes choose to tweet about the addition and sometimes choose not to. It also was pretty difficult to find in my profile how to shut this feature off.
a wonderful way to keep your tweeps updated on what you're reading. sends twitter updates when you add a book to your currently-reading shelf, when you update what page you're on, and when you rate the book on a five-star scale. simple and wonderful.