Looking at this I can't help but think that an SVG version of that would be even more awesome (it'd be kind of a perfect fit). The code that blends stroke and fill colour together could disappear; you seemingly draw circles as paths already anyway, so the circly randomness part would work just the same as currently.
I'd try my hand at converting your code, but my JS is horrible and I'm at work for the next 8 hours :|