I bought Jay Heinrichs' Thank You For Arguing last summer, but never got around to more than glancing at it. I've been reading it at pretty much every chance over the past few days, though. It's absolutely fantastic!
One of the main theses of the book seems to be that people shouldn't think of rhetoric as manipulation, and Jay even does little sidebars to point out when he's using techniques within the book to convince you of his points, but I still can't help but feel manipulated. Ah well, it doesn't stop me from wanting to practice my rhetoric more.
