I received "Zone of Control" for Christmas, as it had long since been on my wishlist. I'm thoroughly enjoying it so far. It's a great compilation of articles on the whole gamut of wargaming, from the creation of games like Starfleet Battles and the history of Avalon Hill, to statistical modeling and design, real-world use, and insights on their impact and usefulness. It's both deep and broad in it's scope and hugely insightful. I can't recommend it enough.

Edit: This is one of the books mentioned in the article.