If you have your hands on Apple's Mac OS X 10.5 (a.k.a. Leopard), head over to your iTunes Visualizer, select "Jelly" and turn on Visualizer. Your screen will fill with some amazing visuals, much like those sampled above. Though it's been a long time since Apple highlighted the iTunes Visualizer in their marketing, it's a lot of fun to see the company's whimsical side.
Jelly is best experienced with Trance, Techno, Electronica or Drum 'N' Bass.