Google Maps gives you API for adding additional map layers. This software implements a map tile server for a heatmap layer.
Please tell me (chad@zetaweb.com) if you'd like a link here.
The Anglican Church in North America is using gheat on their homepage to show their parishes.
VisTrac is using gheat to visualize clicks on web pages.
Russell Neches is using gheat to visualize auto and bike accidents in Davis, CA. The data is parsed from about 10,000 raw police reports.
The Australian Honeynet Project is using gheat to visualize the origin of spam that gets caught in their SensorNET honeypots.
The Conficker Working Group is using gheat to track the spread of the Conficker worm.
This is an animated heatmap of the conficker botnet as found in Australia (one frame a day, unique IPs per frame, with data from the end of January through June, 2009). This was produced using a heavily modified gheat. Here's a Flash example.
