What books would you suggest I read to learn more about rhetoric?

I've always been fascinated in cognitive linguistics and political rhetoric. I've got a ton of Lakoff and Pinker books, who else should I read?

What books would you suggest I read to learn more about rhetoric?
I'm not sure of books, as that isn't a subject of great interest to me. However, I did buy a set of dvd-s from a place called The Learning Company that has a series of college lectures on that subject. They also have many other courses and subjects. They have a website, just google it.

sepal