There is one continent that Google Earth is not at all good for: Antarctica. My first attempt at adding an overlay was for the South Pole, and I quickly learned that the poles are the only places on Google’s Earth where overlays are pointless, due to a quirk of the projection method used.
For Antarctica-related exploring, then, best to use the USGS’s Atlas of Antarctic Research. It has a wealth of layers that can be turned on simultaneously, including some quite precise satellite imagery. It’s not as pretty as Google Earth, but it is useful at these latitudes. (Via T√©rk√©pes Egoblog)