Fresh off a World Cup Final decided by penalty kicks, here are a couple economic articles on game theory and penalty kicks. Because of the setup for penalty kicks, the goalkeeper has to guess which way the striker will kick the ball. Tim Harford writes about the application of Morgenstern and von Neumann's game theory to this problem and cites a study by an economist at Brown that found that individual strikers and keepers were acting according to game theory:

Ignacio Palacios-Huerta, an economist at Brown University, found that individual strikers and keepers were, in fact, master strategists. Out of 42 top players that Palacios-Huerta studied, only three departed from game theory recommendations. Professionals such as the Brazilian Rivaldo and Italy’s goalkeeper Gianluigi Buffon are apparently superb economists: their strategies are absolutely unpredictable and, as the theory demands, they are equally successful no matter what they do, indicating that they have found the perfect balance between the different options.

At a book signing about a month ago, Steven Levitt cited similar research that he'd just completed. He and some colleagues published a paper (PDF) studying predictions of game theory using data on penalty kicks in football and discovered that football players were acting close to the theoretical ideal. The one exception, they found, was that players were not kicking it up the middle as often as they should, perhaps because of the embarrassment that might result from a failed kick if the keeper doesn't dive to one side or the other.