So you want to build your own automated bartender? Next Project Awesome has just the project for you. The Drinkinator is an automated bartender with a Raspberry Pi touchscreen interface. As you can see in the below video, you can pick the drink and size, and the machine does the serving.
You are going to need RobotGeek Pumping Stations, a Geekduino, and a few other parts to get started. You can find more information on this project on GitHub.