A People's History of the United States 1492-Present, Howard Zinn
I really liked this one. Zinn details the history that you didn't read about in school, and as the title suggests, it's from a socialist perspective. Revisionist? I guess that's what this is, but while you might argue with his conclusions, it's tough to argue with the historical facts he presents. I really don't have too many problems with his conclusions. For example, he gives a plausible explanation for the "I Got Mine, Screw the Poor" mentality that's pervasive in the outer 'burbs here in the Twin Cities (and I'd assume elsewhere). This is one of the best books I've ever read.