Improve your Google Earth experience with by downloading any of a number of user-created mash-ups. We've rounded up the 10 best Google Earth add-ons that will help you see maps from centuries past or even take a virtual cruise.
Your city in 3D
Not content with photographing, filming, or otherwise recording every nook and cranny of our planet, some people choose to spend their spare time creating virtual 3D models of real-life buildings to further enhance the immersive nature of Google Earth. Google encourages local governments and colleges to produce 3D models of their cities, towns, and campuses - and for those of us who don't have the resources available to institutions, it provides SketchUp, software with which anyone can airly easily create a 3D model of a house, school, office, shed, or treehouse. The Google Earth 3D Warehouse displays the models, and your models may be selected to become part of the 3D Warehouse layer within Google Earth.
Live orbiting satellites
Going about our daily lives, we give little thought to the thousands of satellites that zoom around above our heads, carrying our communications, transmitting television signals, and sometimes even taking our pictures. The openAPRS database tracks the current location of hundreds of satellites in Google Earth, grouping them into categories such as amateur radio, global positioning, weather, and even military satellites. You'll want to switch on only a few categories at once, however, as the skies above are astonishingly crowded.