Left-click - add a bucket
Right-click - remove a bucket
Middle-click - toggle state space plot
This is a Lorenz water wheel. Freely-swinging buckets with small holes in the bottom are arranged around the outside of a loose wheel. Water flows into the bucket at the top of the wheel, filling it up. As it gets heavier it pulls down on the wheel, spinning it.
This simulation is chaotic: even though the behavior of the system is deterministic it is highly sensitive to initial conditions. The animation you see above is unique: no one saw this particular variation before, nor will anyone again. If you refresh the page you'll be given a new wheel with unique initial conditions (well, one out of the 2^128 possible starting conditions, since this is running inside of a digital computer).
On the state space plot you should be able to see the state orbiting two attractors. It's the classic butterfly image that gives the phenomenon its name. The state space plot will look smoother with more buckets, being perfectly smooth at an infinite amount of buckets. Your mouse cannot possibly survive that much clicking, so don't try it.
This applet requires at least JRE 6.