Google Earth puts a planet’s worth of imagery and other geographic information right on your desktop. View exotic locales like Maui and Paris as well as points of interest such as local restaurants, hospitals, schools, and more.
Previously called Keyhole (Keyhole.com now forwards to Google Earth), Google Earth is an atlas on your desktop. You can view the entire world as a big globe with satellite photography showing how things look. The globe is a 3d object that, as well as being round, shows the topology of the landscape you are currently viewing.
Like Google Maps it lets you enter an address and be taken there instantly. Unlike Keyhole there is a free version that is actually free. The demo of Keyhole decided to chain itself to your computer, and you had to create an unlock code using your email address to run it. Not user friendly, and not very Google.
Google Earth is considerably better than Keyhole and, assuming the place you want to look at has been photographed is an interesting way to waste a morning.
To get the most out of it Google Earth needs a decent internet connection and a reasonable spec pc, but I would recommend everyone have a look, if only to see if you can find where you live.