[UPDATE 1430 ET: corrected attributions] A couple of researchers from UC Berkeley contacted me to share some visualizations they have developed for Google Earth using LIDAR data (a kind of optical radar system that allows you to collect 3D information in digital form of outdoor scenery). Martin Isenburg and Jonathan Shewchuk have published some of their results at this web page (which is at UNC where Martin got his PHD). They are using view-based network links to let you view image overlays of LIDAR data, and they have developed tools so they can generate isocontours from the LIDAR and generate contour tiles viewable in Google Earth as well.
Check out this example of LIDAR aerial imagery overlayed for Toronto, Canada . As you zoom in you will see the tiles of imagery they have available. The imagery has a shaded relief appearance which reflects the presence of 3D shapes. You can see trees, cars, and even people in the data.
Also, try the contour example they have for Mount Saint Helens in GE. You can see that the interior of the volcano in GE does not reflect the full extent of terrain in the interior (tilt your view in GE to see this).