Playing with the HTML canvas by way of Clifford Attractors. First, evaluate:

x1 = sin(A * y) + C * cos(A * x)
y1 = sin(B * x) + D * cos(B * y)
      

...then do it again, but a lot. Plot the results. Note the parameter space is tetchy and can give blank results. You can also pre-render at higher quality for more pretty making.

Some presets thanks to the formidable Paul Bourke.