rationalskepticism.org

The Worldly Philosophers is definitely the top of the list. It was the first book I read, back in the early 90s, that let me understand that econ could be interesting. It includes all the cool *human* stuff I had take out for space, like Veblen's womanizing, Smith's colossal absentmindedness, Keynes's bisexuality, Marx's carbuncles. . . .

E. Ray Canterbery's A Brief History of Economics is another good source.