helpful_links

# Choosing color palette for heatmap
http://gka.github.io/palettes/

# Chroma.js API
https://github.com/gka/chroma.js/blob/master/doc/api.md

# Some kartograph tutorial with nice code
http://vumaasha.github.io/codehook/kartograph/geomapping/2013/11/24/using-kartograph.html

# kartograph.js API
http://kartograph.org/docs/kartograph.js/

# kartograph choropleth source
https://github.com/kartograph/kartograph.org/tree/master/showcase/choropleth