A rough implementation of a Voronoi diagram which examines 1 pixel per loop and draws a circle with the colour based on the distance between the various points moving around the screen.

Cartridge code (250 chars):

q={}w=128r=rnd
for i=0,8 do
add(q,{x=r(w),y=r(w),vx=r(2)-1})
end::v::x=r(w)y=r(w)c=0l=w*w
for i=1,9 do
b=q[i]d=(x-b.x)^2+(y-b.y)^2
if(dend
if(btnp()>0)run()
for i=1,9 do
p=q[i]
p.x+=p.vx/1000
if(p.x>w or p.x<0)p.vx*=-1end
goto v