How much space do I get, here? My list is HUGE.
The first book I ever read and had to immediately re-read was "Armor" by John Steakly. I have of course read J.R.R.Tolkien's "The Hobbit" and the Rings Trilogy three times, at least. I'm easily on my 20th re-read of Dale Carnegie's "Win Friends and Influence People." I also like to re-read the current conservative standards like Michelle Malkin's "Unhinged" and "Culture of Corruption" as well as Jonah Goldberg's "Liberal Fascism" (which should be required reading in any American History class).
I went through a period in my late teens when I read all of the John Norman "Gor" novels in print (17 books back then, now up to 27, I think) 3 or 4 times. David Weber and David Drake are my current fiction favorites. I've read Weber's 8 tome "Honor Herrington" series (which begins with "On Basilisk Station") twice, and I'm on my 12th re-read of his "In Fury Born."
I'd better stop now, because I could go on like this for hours.