An intelligence oriented reading list, specificly aimed at folks entering the U.S. DoD intelligence world;

-The Craft of Intelligence by Allen W. Dulles (THE primer on intelligence). This is an excellent discussion of intelligence from requirements through collection to analysis. Dulles presents it so well that, despite the clear Cold War spin, the relevance is timeless.

-The U.S. Intelligence Community by Jeffrey T. Richelson (A comprehensive work on U.S. Intel; be sure to get the 5th edition).

-My Adventures as a Spy by Robert Baden-Powell (fun and motivational, but lots of valid nuggets, and can be found as a .pdf online).

-Aids to scouting for N.-C.Os. & men by Robert Baden-Powell (avail from www.military-info.com, there is a .pdf floating around though) (a valuable historical perspective; how it worked before radio and PowerPoint).

-Handbook of Intelligence and Guerilla Warfare by Alexander Orlov (how the other side, the USSR, used to do it, kind of like studying course notes from the O.S.S. or early CIA).

-I can't think of a single, good work on analysis for less than $100, but should I see one, I'll forward it. The Wikipedia (http://en.wikipedia.org/wiki/Intelligence_analysis) in intel analysis isn't bad, and has links to better materials.

-The Compleat Strategyst: Being a Primer on the Theory of Games of Strategy; by J. D. Williams. This is the best book on game theory for liberal arts majors (including history majors). What this provides is a language from discussing conflict and politics that is low on emotion, allowing more level-headed discussion. (If you have the maths, "Games and Decisions: Introduction and Critical Survey" by R. Duncan Luce, Howard Raiffa is better, but sigma notation makes my head spin.)

-Statistics for Dummies. Numbers do, in fact, lie. But with a little preparation, they don't have to lie to you.