David Ewalt's Of Dice and Men is a wonderful, energetic and personal history of Dungeons and Dragons. Ewalt — an editor and writer at Forbes magazine — played D&D as a geeky adolescent, gave it up through his early adulthood, then fell in love with it again. Dice and Men is the story of his journey in D&D and the history of the game itself.
Ewalt is a great writer, and has the magazine-feature-writer's gift of weaving together the personal story and the wider tale, with lots of smooth transitions between the subjects and fascinating interludes. The story of role playing games is itself a fascinating tale, with an improbable origin in the confluence of two strains of tabletop strategy games.
Ewalt has dug deep into the history of the genre, unearthing details about the rise and fall of TSR, a company that experienced an early example of the dotcom era's "hockey stick" growth, followed by a precipitous collapse due to mismanagement, infighting, and a change in the wind that caught the company offguard (this section was worth it just to learn where my beloved D&D coloring book came from).
As someone who was completely obsessed with the game during its heyday, and who struggled to make sense of the strange evolution of its many tie-ins, such as the TV cartoon show and the various Basic and Advanced editions, as well as the relationship that these bore to strange, rare proto-RPGs like Chainmail, this was especially fascinating — providing the missing puzzle-pieces so that it all made sense.
Ultimately, Ewalt is on a quest to pull the whole phenomenon of RPGs into context — what made it such a business and cultural success, how that relates to other phenomena like LARPing, video games, and science fiction and fantasy literature. It's an exciting account of the ultimate RPG campaign — the quest to popularize RPGs themselves.