I came across revoid.be/codebrush/ a generative drawing experiement earlier today, and got a little bit hooked over lunch.

Its pretty simple, there are 4 different brushes and several colour options. Drawing is quite intuitive, the faster you move your cursor the larger the brush stroke. It does take a little working out, but after a while you can drawing with an idea of the outcome, although at first glance it looks entirely random.

And at the end, you can watch your drawing redraw itself.

Looking into it a bit more know whilst writing this, and seeing as its done in html5/css3  and javascript I see it works on mobile devices and supports multi touch as well, although I've not tried it on my iphone.

Gwen Vanhee has done a great job and its well worth a little play.  Here is what I came up with: