If you really want to entertain your cat to the point that it can go insane, just buy the BadaBeam toy for $20. Its a cone shaped device that will project a mind-buggling (for a cat) laser dot around the room to keep your cat very occupied.
Via OhGizmo
We have 4 cats. Three of them are 3yr. and less. One of them really likes laser beams to chase. The beam on the Ba-Da Beam moves too fast to get their attention. Our cats just sit and look at the machine. If it is on the floor, and set to show on the floor, the circle is way too small to attract attention. I say : Not worth the $20.00 we paid.