Fermat's Last Theorem by Simon Singh (I read this as a child and decided then and there that I ould become a Mathematician)
The Mormon Murders by Steven Naifeh and Gregory White Smith (I read this during my journey out of the WT)
Perfect Rigor: a Genius and the Mathematical Breakthrough of the Century by Masha Gessen (a biography of Grisha Perelman)
Ishmael; My Ishmael; The Story of B three books by Daniel Quinn (made me think a lot about the state of humankind, how we came until here, and how we should go on)
Way of the peacful Warrior by Dan Millman (especially for athletes, but also for all who want to succeed anywhere)