Paint a canvas with math! you have a 1000x1000 pixel area to paint, starting with 0,0 in the top left. Try x*y or x|y to start.
If you draw x you can see how different values map onto colors. It will try
to guess when to redraw but you can force it if it guesses wrong.
Some more recpies:
(x * y > 200000 ? x : y) + x % y
(y+a*.0001)*i*.01 * ((x)*.04)