Which Books Have you read more than once?

John at SFSignal asks:
What books have you read more than once?

I haven’t re-read as much lately as I might like, mainly because of time. I have a “To be read” pile that is 150 books and counting, and so I eschew re-reading old novels in favor of new ones as much as possible.
Still, noteworthy books I’ve read multiple times:
* Silverlock, by John Myers Myers. Call me old fashioned, this is still one of my favorites. And I still need to run a game set in the Commonwealth someday.
* Harry Potter and the Sorcerer’s Stone. I read this one a couple of years ago, and re-read it in my effort to read the entire series (short of DH).
* The Chronicles of Amber, by Roger Zelazny. Because of the superb writing, to get Amber game ideas, because I love his work.
* The Tschai novels, by Jack Vance. These were among the first novels I read when I started SF (thank you, brother!). I read them a couple of times since, most recently in the new omnibus edition.
* The Color of Magic, by Terry Pratchett. Again, I read this some years ago, and then re-read it in my ongoing efforts to read the entire Discworld Canon.
* Years In The Making: The Time-Travel Stories Of L. Sprague De Camp (L. Sprague De Camp)
I count this as a re-read because I read almost all of the stories in other contexts, and read the volume mainly for that pleasure.

Coming up eventually in my reading queue will be some more re-reads. I have some Jim Butcher to read (I read the first novel and will re-read it when I start *that* series), as well as De Camp’s Enchanter novels. In general, though, I try to read new stuff, to reduce that ever growing pile…
And I didn’t count the re-reading of “grazing books”, books I like to flip through casually (from historical atlases to GURPS worldbooks). I’ve re-read those a number of times.