I present to you one of my favorite, and most challenging, personal projects: The Aufbau Principle Ugly Christmas Sweater. I purchased the sweater online, and rigged it up with a Sparkfun Lilypad, and a variety of colors of LEDs. I programmed the Lilypad to produce different effects for the LEDs. This project required a variety of skills, such as concept of design, construction, circuit diagrams, programming, sewing, and extreme patience. It is powered by a Li-ion battery, and is machine washable once the battery is removed.
Below I've included a video of the sweater blinking.
I'd very much so like to make more "ugly Christmas" sweaters, so if you are interested, please contact me, and we'll see what we can come up with.