Clifford-Attractors is a project mainly written in JavaScript, it's free.
Using HTML canvas to generate interesting blobs
Using canvas to generate interesting 2D blobs. Got the idea and formulae from paulbourke.net.
a, b, c and d are numbers that plug into the formulae. Just play around! The web console in Chrome or Firebug prints the actual values if you need them.
Scale makes the shape bigger or smaller.
Opacity is self explanatory.