littleBits i28 accelerometer

Skeptical at first that a little Bit could actually sense motion this well, but waving it around really does light up the bargraph in real time. My nephew spent a solid hour just watching the LEDs react to how fast he moved it.

Snapped this to the bargraph and my kid spent an hour just waving it around to watch the lights jump. The response to speed changes feels quick and smooth, no lag when you tilt it. Ended up buying a second one for my own tinkering.