"Debt: The first 5000 years" completely changed the way I view money, society, and relationships. "The selfish gene" changed the way I define life, opened my eyes to virtual life, and morality of selfishness vs. altruism. "Into the Cool: Energy Flow, Thermodynamics, and Life" changed the way I view the life and material existence. Whereas before I viewed them as two separate domains, after I see them as a spectrum. Chinese classic taoism treaties: "Dao De Jing", and "Zhuan Zi", offers a via-negativa way of thinking and view of existence, the values are beyond words.
Also recommended in this reply