I was showing this to a friend a couple of years ago when we accidentally discovered, to our delight, that it's orientation-aware. If you're using Chrome on a Mac laptop, try tilting your machine to see how it affects the elements on screen. (Theoretically, it should also work on most iOS devices and other laptops with motion sensors, but I haven't really tested it extensively.)

Prior to that discovery, I had no idea that a non-mobile browser could access motion sensor data. Turns out that on a MBP at least, the data comes from the Sudden Motion Sensor[1], which is also responsible for parking disk drive heads if you drop your laptop. Pretty cool stuff.

[1] https://en.wikipedia.org/wiki/Sudden_Motion_Sensor

A couple more links for the curious:

http://www.html5rocks.com/en/tutorials/device/orientation/

https://developer.mozilla.org/en-US/docs/WebAPI/Detecting_de...

EDIT: Almost forgot, but I actually created a little drawing experiment based on this: http://peterjmags.com/accelosketch/. Try clicking around and tilting your laptop to draw.