Oh, Dave, real bibliophiles use LibraryThing [librarything.com].
But! Yesterday, a kind librarian reader pointed me to a site called "Good Reads". It's a social network built around books and book lovers. I went to check it out, and there were already 80 reviews for Sheldon books in their system! So let's try it out: If you're already on Good Reads, swing by the Sheldon book page and rate the books you own.
So far, "Pugs" is in the lead, with a 4.57 out of 5 points!