Typography for Lawyers is the layman's guide to good typography. While some of the information is quite specific to the law profession, the use of semi-colons, small caps, "curly" quotes and so many other simple facts are universally applicable. I would recommend this to anyone in a position to produce printed documents -- bankers, insurance agents, doctors, et al. Good typography is not just for designers.
(Thanks to Madeline at Tag Team Tompkins for the recommendation)