I haven't had anywhere near as much time to read as I'd like to lately - but books that changed me somehow (in no particular order)

Animal Farm - Orwell

The Power that Preserves - Stephen R. Donaldson - It's a 600 page fantasy novel that I read in one sitting (14 hours) when I was 13 or so.  It seems just this side of crap to me now, but it hooked me on books.

A Day in the Life of Ivan Denisovich - Solzhenitsyn