I can count on two hands the number of books I've read more than once.

"The Structure of Scientific Revolutions"
"Objective Knowledge"
"I, Robot"
"Robots of Dawn"
"Bolo"
"The Fellowship of the Ring"

I *have* read "Call of the Wild" and "Bicentennial Man" and a few others 3 or 4 times, but that was only because I read it aloud with the kids.

"Robots of Dawn" I read by accident the 2nd time. Great book, but I didn't realize I had actually read it before until I got to the end.