So we have experienced Google Earth (love it), but have you been to Google Moon or Google Mars yet?
Google Moon is from a couple years ago. It is a map of the moon's surface made up of images provided by NASA. The map shows the landing sites of Apollo Missions 11-17. Be sure to zoom in all the way (clearly someone has a good sense of humor).
Google Mars was launched about a year ago. It is a bit more sophisticated than Google Moon. Maps of Mars are viewable in Elevation, Visible, and Infrared modes. The map is annotated with information about physical features and regions, as well as spacecraft landings and images. There are some plug-ins available to overlay the map of Mars onto Google Earth so that you can spin it but they require some fussing around with your Google Earth settings. Google says that they are planning to incorporate Mars into future versions of Google Earth.