Okay, so i was bored and messed with my HD2 with Wp7. i discovered that on the xbox live avatar screen if you tap, hold and swipe left and right, BUT NOT LETTING GO, makes it look like there is an earthquake and get this....YOUR AVATAR RESPONDS! Mine just looked dizzy and fell to the floor haha. you can also shake it and oddly enough it does some lulzy dance moves.
Try it out and post results!