Lord of the Rings probably tops my reread list -- many times but not since the movies came out.

The Lattimore translation of Homer's Iliad and Odyssey.

In science fiction, Asimov's Foundation trilogy (but not the subsequent additions). Similarly, Herbert's Dune (but only the first in that over-done series). Also the Mote in God's Eye and Lucifer's Hammer. And of course Vonnegut's Cat's Cradle.   

Of short stories, Twain's A Cure for the Blues -- one of the funniest essays ever -- and all of Saki.

There are others. I tended to reread novels when I was younger, not so much since I passed 50. Too little time now; too much on my waiting to be read list, I suppose.