Here is a nice network link worth keeping: Aeronautical Sectional Charts of the United States, uploaded to Google Earth Hacks by Forkboy2. He (she?) writes:

Improvements include much smaller image files for better performance (and no loss of image quality), changed the icon from a generic push pin to an airplane, changed it to a network linked KMZ so that any future improvements will update automatically on your system, and some other surprises.