How to entertain a budgie or parakeet

Overview
The are 4 way to entertain a budgie or parakeet.

Bells
They are fascinated by shiny things and the ringing is at they same frequency as the cheep at.

Ripped white paper
They like cutting it up in the beaks, sitting in it and kicking it about with hire feet.

Balls
They, for unknown reasons, like rolling them about a lot.

Mirrors
They are of the opinion that it is another bird, not their own image, hence it's a instant companion.

Also see

 * 1) Bird welfare