Some personal favorites, descriptions stolen from Amazon:
"A People's History of the United States," Howard Zinn
Known for its lively, clear prose as well as its scholarly research, A People's History of the United States is the only volume to tell America's story from the point of view of -- and in the words of -- America's women, factory workers, African Americans, Native Americans, working poor, and immigrant laborers.
"Blood Rites," Barbara
In Blood Rites, Barbara Ehrenreich confronts the mystery of the human attraction to violence: What draws our species to war and even makes us see it as a kind of sacred undertaking? Blood Rites takes us on an original journey from the elaborate human sacrifices of the ancient world to the carnage and holocaust of twentieth-century "total war." Sifting through the fragile records of prehistory, Ehrenreich discovers the wellspring of war in an unexpected place--not in a "killer instinct" unique to the males of our species but in the blood rites early humans performed to reenact their terrifying experience of predation by stronger carnivores. Brilliant in conception, rich in scope, Blood Rites is a monumental work that will transform our understanding of the greatest single threat to human life.
"Pilgrim at Tinker Creek," Annie Dillard
An exhilarating meditation on nature and its seasons-a personal narrative highlighting one year's exploration on foot in the author's own neighborhood in Tinker Creek, Virginia. In the summer, Dillard stalks muskrats in the creek and contemplates wave mechanics; in the fall she watches a monarch butterfly migration and dreams of Arctic caribou. She tries to con a coot; she collects pond water and examines it under a microscope. She unties a snake skin, witnesses a flood, and plays -King of the Meadow' with a field of grasshoppers.
"Zen and the Art of Motorcycle Maintenance," Robert H. Pirsig
Arguably one of the most profoundly important essays ever written on the nature and significance of "quality" and definitely a necessary anodyne to the consequences of a modern world pathologically obsessed with quantity. Although set as a story of a cross-country trip on a motorcycle by a father and son, it is more nearly a journey through 2,000 years of Western philosophy. For some people, this has been a truly life-changing book.