This demonstration generates beautiful pictures by drawing lines between points on a circle.
Imagine a number of points N equally spaced on the circumference of a circle. The points are numbered from 0 to N-1. From each point n a line is drawn to a point on the circle corresponding with the product (or its remainder after divided by N) of n * m, where m is the multiplier.
Arrow up and down: decrease/increase number of points.
Arrow left and right: decrease/increase multiplier
r: restore