Lean Poker is a day long coding challenge that's not only fun, but also provides a safe environment in which you can practice continuous deployment and fast delivery of valuable software.
This is how it works: You and a small group of strangers are going to develop a bot in a language of your choice, that plays poker against other bots. The bots start playing at the same time as teams start coding. From that point on the teams aim is to deliver improvements to their bot in tiny iterations to make sure that their robot is always just a tiny bit better then that of other teams. Points are collected through the day by each team, and at the end we will have a winner.
Please check out http://leanpoker.org for more information.