HeatCanvas is a heat map for web browser, written with Canvas and WebWorker.

Take a look at this too <a href="http://www.patrick-wied.at/static/heatmapjs/" rel="nofollow">http://www.patrick-wied.at/static/heatmapjs/</a>

This is a great idea, and I can well imagine using it.<p>But the Google Maps integration seems a bit shaky at present -- the overlay generally fails to refresh when I scroll the map (FF 4.0.1 on Mac).

Very nice. How much data does it handle before it starts getting sluggish?

Here is an idea for a weekend project: an open source Crazy Egg.