Google Earth is turning out to be a great resource for scientists to visualize and communicate the phenomena they study. You can see the migration patterns of endangered and other threatened animals, based on data collected by the Commission for Environmental Cooperation. (The image above shows the range of both the Northern spotted owl and the Mexican spotted owl).
Anybody can take geographical data and turn it into a layer on Google Earth. Scientists are doing this in droves. You can also track storms, the paths of solar eclipses, volcano activity, arctic ice melting, bird flu mutations and biomaps of emotional stress levels in different cities (see this Popular Science article for more info).
Since these are all KML files, they could be made into layers on the regular Google Maps as well. Although they wouldn’t look as cool, more people would see them.