Why re-invent the wheel when you can re-invent the ball. That seems to be the thinking behind Sphero. 

At $170 Sphero is halfway between Wall-E and your favourite pet. You control Sphero with your phone and can let it roll in water, change colour, and even impersonate Evel Knievel.

It may seem stupid, it may indeed even be stupid, but credit where credit is due there is a lot of innovation that’s driving this ball of stupidity.

Inside the sealed white shell is a tiny robot that uses a gyroscope to balance on two wheels. The robot drives up the side of its own shell creating forward and upward movements. Think of it like a Segway stuck inside of a ball. The trick is that it runs on gravity. 

wires, or battery compartments. Instead Sphero has its own built-in batteries that are charged by passing energy through the shell itself.

The charging station is basically a copper coil, which generates an alternating electromagnetic field and Spehro converts that invisible field into electricity.

Where it really gets fun, apart from torturing your cats and toddlers, are the augmented reality games. Sphero uses your phones camera to overlay a game environment, with say zombies, to give you a unique game play experience. It's fun but gameplay can be challenging. After all you are trying to control a ball that has a tendancy to run into objects.