Originally written in the desktop version of Processing, with PDF export, and intended to be used to generate backgrounds, “A Jackson Pollock-esque Art Generator” has now been ported to Processing.js, running in any HTML5 canvas compatible browser. Simply click and drag to waste time create beautiful artwork. You can even export an image of your masterpieces!

Available (with full source code) here:
https://mpetroff.net/files/processing/backgroundgenerator/