I was wondering if anyone knew of an Open-source project for displaying numbers for the US states.

Specifically, you always see these graphics with California in dark grey, Montana in green, etc. Based on some sort of criteria. 

I'm thinking of building one for a site I maintain, but I was hoping I might not have to reinvent the wheel.

<http://upload.wikimedia.org/wikipedia/commons/7/70/World_map_of_Energy_consumption_1979-1981.svg>

Something like the above, but for the US, and you can define your own criteria?