Book: Land Navigation Handbook
Land Navigation Handbook: The Sierra Club Guide to Map, Compass, & GPS by W.S. Kals is a fabulous technical book for any beginning or intermediate navigator who wants to learn not only the hows but also the whys of orienteering. The book offers more than just detailed instruction on the particulars of map reading; its aim is to help readers ultimately learn to interpret maps and understand why they look they way they look. The sample pull-out map is a helpful tool for the book's examples and tests of the reader's newfound skills.
Two chapters discuss how compasses work and how to use them correctly, including a diligent explanation of how the difference between "true north" on a map and magnetic north can affect orientation (ore deposits deep in the earth pull a compass needle off true north). There is also a chapter on how altimeters work and how to navigate with them. And of course there is a considerable discussion of how a GPS works, how to choose and use a GPS, and the flaws of GPS navigation.
But perhaps the coolest chapter is in the back. It describes how to get your bearings the old-fashioned way: from the sun and the stars. It's survival-oriented, of course, but it also makes for a wonderful homage to the explorers who wandered these mountains and plains far before we did.