Create Your Own Heat Maps - Google Maps

You can now make your own heat maps using the system that I created for the Energy Justice Communities Map.

http://www.campusactivism.org/heatmap/heat.php

Currently it is running very slow. The code is faster if you run it on your own computer (possibly 10-100 times in my case), and it might help to give mysql a lot of memory (notably for its key cache). You can download the source code.

Typically people suggest using an intensity mask to create a heat map. That is probably a superior method (faster and maybe better looking), though I'm not sure if it works in my case - as I wanted to measure the impact of a point (coal power plant) on the entire US - not just its immediate surroundings.

Heat Map Intensity Method (with instructions for developers)
http://dylanvester.com/post/Creating-Heat-Maps-with-NET-20-(C-Sharp).aspx

Another Heat Map (for users)
http://en.tixik.com/tools/heatmaps

Another Heat Map (for users)
http://www.openheatmap.com/