Fractals are shapes with a non-integer dimension.

Marble Marcher - Video game demo that uses a fractal physics engine and fully procedural rendering to produce beautiful and unique gameplay unlike anything you've seen before. (Video)

Chaos - Visualizations connecting chaos theory, fractals, and the logistic map.

Chaos Game - Method of creating a fractal, using a polygon and an initial point selected at random inside. (Code)

Playing with Chaos - Programming fractals and strange attractors in JS.

Clam - High-quality fractal viewer.

Buddhabrot - Render a Buddhabrot fractal (an algorithm invented by Melinda Green).