What type of hardware could make a ball tilt or roll? I wanted to know what type of component or module I could use to make a hollow ball move.  I have these hollow plastic balls (think empty easter eggs) that I was going to put a nano in and a sound detector and was just hoping to just get it to move.  I prefer a sort of a tilt left and right effect, but if it just rolls randomly that would work as well.

I was thinking just a simple vibration, but it doesn't really shift the ball at all, so I'm at a loss without building something quite complex with magnets or something.  Perhaps a motor stuck to the side?
The ball moves are made by a simple physics principle called Conservation of Angular Momentum. The angular momentum is a property that has any object that rotates and is proportional to its mass and velocity.
To make a ball move you should play with this momentum, using its simplest application, the mechanical gyroscope.
The mechanical gyro is made of a heavy disc rotating at high speed, modulating its velocity you can change the momentum and create a force that will move your sphere.