I built my first arduino project this month! I was Alina Starkov, the Sun Summoner, for Halloween, so I built accelerometer controlled LED gauntlets so I could turn the lights at my wrists on and off with gestures.

The instructable I wrote is here.

I had an enormous amount of fun, and the arduino system (I was using LilyPad, since I needed it to be sewable) was very beginner friendly. Glad to answer questions/provide encouragement!

Oh, and here are pics of the final costume. (I ran into a HJPEV at my Halloween party)