AHRobot is an air hockey robot player build using standard RepRap 3D printer parts: electronics, motors, drivers, bearings, belts... and a DIY air hockey table.
The robot has three motors: two for moving its mallet across the y-axis and one for movement along the x-axis. Jose Julio wrote the drivers for the motors in Arduino. He then color-coded the mallet and the puck, installed a PlayStation Eye camera and wrote a program in C to make his robot see. Finally he wrote another Arduino program that predicts where the puck will go so that its motors can react appropriately.
Another neat thing about Jose Julio's setup is that the table uses two old PC fans to create a cushion for the puck to slide on.