So you're graduating from college (probably engineering) - Congratulations! Remind everybody that you're an awesome engineer by making your mortar board (graduation cap) light up!
Grab an Arduino, some LEDS (I used 8 green, 4 yellow, and 1 red), 330ohm resistors (one for each LED), and a protoboard. Wire them up as shown in the attached schematic, arranging the LEDs on the protoboard however you choose. Hook this up to the arduino, and add a 9V battery pack for power.
Once you've got that all wired up, download my source code
(customize as needed), and load it onto your arduino. You're ready to blink your way through graduation!