This applet displays moving, symmetric patterns that are similar to what might be seen in a Kaleidoscope. Each pattern lasts about 10 seconds. Many aspects of the pattern are chosen at random, and it can vary from as simple as one unmoving figure with no symmetry to a colorful, complex, 8-way symmetric pattern. Keep watching and you'll probably see something you like.
Click here to see the source. This applet is written as an extension of a simple animation framework. You can also look at the source for that.
You can find more of my Java work at http://math.hws.edu/xJava/.