An interactive physics simulation of Brownian Motion! Brownian Motion is the random motion of particles that are suspended in a gas or a liquid. Drag the first slider to see what's going on behind the scenes and play around with the physical parameters. You can also download a snapshot if your particles draw you something inspiring.
Watch the introductory video: Brownian Motion Video.
Watch the MinutePhysics on Brownian Motion: Albert Einstein: The Size and Existence of Atoms.
Note: There is a lot of physics going on here... if it seems sluggish, try it on a desktop browser with Google's Chrome browser.