http://www.google.com/earth/index.html Google Earth allows you to travel the world through a virtual globe and view satellite imagery, maps, terrain, 3D buildings, and much more. You can navigate to locations anywhere in the world. And it is free to download.
So you have Google Earth on your computer and you want to know how to use it? Click the link below for a useful guide to getting starting navigating around Google earth.
For classroom resources click on the link below:
The link below provides 10 ideas for using Google Earth with your class:
Links to a variety of Google Earth classroom resources
http://olliebray.typepad.com/olliebraycom/google_earth/ Ollie Bray has provided a number of useful tips for using Google Earth in the classroom.
Creating Projects in Google Earth is a post by Tim Stahmer specifically about Google Earth layers, but also with a host of links to associated resources for using Google Earth in the classroom.