HeatmapTool.com

Try it out...

On the right is a heat map of 289 campgrounds in Maine¹. Explore some of the options HeatmapTool has to offer by changing any of the parameters below:

Color gradient (built-in, or custom):
Custom gradient - start (hex color):
Custom gradient - end (hex color):
Gradient tiers (false, or 1-256):
Spot radius (1-128, in pixels):
Scale - minimum (auto, or a number):
Scale - maximum (auto, or a number):
Scale - dimming (between 0-1):
Heat map opacity (between 0-1):
Heat map feathering (between 0-1):
Background color (hex color):
Background opacity (between 0-1):

¹ http://www.poi-factory.com/node/27786