Google Earth - Very Cool.
I have been playing around with the free software Google Earth and I must say I am very impressed. There are some tiny glitches here and there (like a lake being highlighted in one place if you have the bodies of water toggled on, and the photo of it being slightly off side.) but it is a seriously impressive tool.
I did not have any experience with Google Maps but here is how the Google Earth program works. Lots of satellite and aerial images (of various quality and age and updated periodically) are stitched together to form the globe. Topographical information is incorporated so that you can get a sense of what the Grand Canyon looks like or how far and big the hills and mountains are near your home town. You can toggle on or off things like roads (highways and street maps are overlaid on the images), borders, geological markers like volcanoes, shops, schools, churches, restaurants, you can search the location you are in for search terms like the name of some business you have heard about and as you zoom in towards it a pop-up balloon will provide a link to the business' web site if you want to see it. You can type in a street name or a postal code and it will zoom in to the correct portion of the street map. You can type in a new city or town name and it will zoom out and fly to the new location giving you a sense of geographic perspective. Some cities (American only so far, I believe) have included 3D models of their larger buildings.
You can bookmark specific places and I can imagine a huge number of uses for this; not to mention that it is just really cool to play with. I noticed some regularly spaced little dots in Libya which I thought might be nuclear missile silos but were just circularly irrigated fields in the desert. Boy was my face red after calling the Pentagon on that one.
This software is like Zinthos - "Its exactly what you need, exactly when you need it." (obscure anime reference.)