A new series by Wolfgang Baur; ostensibly about D&D, but useful for other games as well.
Black Gobbo: Why We Play the Game
Theoretically about Warhammer, but applies to pretty much everything. In a nutshell: if you are a spoiled, pissant punk at the game table, you always lose ... if you generous, relax and have fun, you always win. I've met my share of people who could stand to learn this.