Google.org launched some incredible KML recently that describes potential geothermal energy resources in the United States. This presentation utilizes the Google Chart API. Read about this effort or view this presentation in Google Earth.
This KML is both very slick and very effective. Be sure to play with the settings in the Places panel to see 3D depictions, energy resource depth and animations. Each chart icon opens a placemark balloon that provides additional information about geothermal resources in the given state.