|As posted on the GPS Visualizer website:|
"This page will help you create alternate overlays for use with Google Earth. It's true that Google Earth already contains high-resolution satellite data for many cities (and even some non-urban areas); but in much of the U.S., the USGS black-and-white 1m aerial photos provide better detail, and the USGS topo maps contain information which is not available in GE in any form. For the rest of the world, pictures from the "Terra" and "Aqua" satellites might be of interest, if your data covers a large area; they transmit up-to-date (but low-resolution) images back to earth every day.
If you try to generate an overlay and get an error about the map server being unavailable: my sincere apologies, but it's out of my control. TerraServer-USA.com sometimes goes down for hours or days at a time, and the USGS data is simply unavailable when that happens."