http://ludonaut.tumblr.com/post/82574421917

hypnoellipses.pde

float f;

void setup() {
  size(500, 500);
}

void draw() {
  smooth(8);
  translate(width/2, height/2);
  strokeWeight(10);
  for (int i = 30; i > 0; i--) {
    ellipse(0, 0, i * 30 + 25 * sin(i+f), i * 30 + 25 * sin(i+f) );
  }

  f+=0.0523;
}