Blog post | Credits and license below
The original version of "Splatter" was by Michal Migurski:
http://stamen.com/projects/splatter (the URL is not available anymore). Hats off to Michal Migurski!
Anyone may redistribute this work under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License. Details on this license are available at http://creativecommons.org/licenses/by-nc-sa/2.5/.