Recently I built a motion sensitive LED belt for a dance performance by my wife. In case it is of interest to others, this post will briefly describe how I made it.
I started with the LED belt kit by Adafruit:
for which they supply an excellent tutorial:
To this I added a 3-axis accelerometer, the ADXL335 from Adafruit:
Adding the accelerometer is very simple. The 3V in and ground are soldered with short wires to the corresponding pins on the Atmega32u4 breakout board, and wires from the X,Y, and Z outputs can be soldered to the F4, F5, and F6 pins (see http://github.com/adafruit/Atmega32u4-Breakout-Board for more details or http://www.adafruit.com/datasheets/af_at32u4bb_pinout.pdf for a good diagram).
After a lot of tweaking, here is the code we actually used for the performance:
Here is a short video (with a special guest star - our dog - in the background):
Sorry about the graininess - hopefully I can get a somewhat better version soon. I'm also hoping for good closeup pictures of the soldered connections.