Schwartz maintains we need fewer choices in salad dressings (he counted 75 varieties at his local supermarket) and more in political parties. He cites wonderful examples of how consumers shut down in the face of too much choice and opt not to choose at all. It's thought-provoking, even if you don't agree with him (which I'm not sure I do).

Also, check out Human Nature by Malcolm Gladwell, the author of the fascinating Blink. It'll challenge your faith in market research by convincing you that people don't say what they really think and that their actions are often very different than their intentions. His dissection of the failure of New Coke is particularly interesting.