I just noticed that Harry Frankfurt's classic essay "On Bullshit" has been published as a (very short) book. You can read the orginal essay here, or go see an interview with Frankfurt about the book here.

Lying is usually understood to involve saying something that you believe to be false, although some might add that what you say must actually be false. Misrepresentation, I think, involves saying something that you believe to be true, in order to get your audience to believe something that you believe to be false. Bullshit, according to Frankfurt, involves saying anything at all, with complete disregard for whether it is true or false, in order to get your audience to believe what you want them to believe.