The Lucifer Effect: Understanding How Good People Turn Evil (Random House, 2007) by Philip Zimbardo.
"In this book, I summarize more than 30 years of research on factors that can create a "perfect storm" which leads good people to engage in evil actions. This transformation of human character is what I call the "Lucifer Effect," named after God's favorite angel, Lucifer, who fell from grace and ultimately became Satan."
An excellent book!
You can get a taste of it here from The Engines of Our Ingenuity on NPR or go to the official website here.
I have just begun...
The Burning Tigris: The Armenian Genocide and America's Response (HarperCollins, 2004) by Peter Balakian .
Peter Balakian's The Burning Tigris places the story of the Armenian genocide in its larger historical context, which includes the international response and the emergence of a fledgling human rights movement that, two decades later, turned its attention to events in Nazi Germany. Balakian's book also illustrates how quickly the victims of history are pushed aside and forgotten in the greater geopolitical picture. Adolf Hitler, addressing his generals as they prepared to invade Poland in 1939, told them to be as ruthless as Genghis Khan and ominously asked, "Who today ... speaks of the annihilation of the Armenians?"
Read the whole article: "Do-gooder dilemma: the limits of humanitarian intervention" by Victoria Barnett here. (from The Christian Century, August 10, 2004)