There is no contest for this one …
They are the biggest, best, you can still get web sites listed for free and they are constantly developing innovative ways of the making the searching experience, well an experience.
Take Google Earth
“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.”
You can download a free version at http://earth.google.com/