Google Earth is a computer program that brings a virtual earth to your desktop. http://earth.google.com/ It can be downloaded free from Google and it is quite simple to use. Not only is it a cool way to visualize the earth and 'see' cool geographic locations, but it is a program that will let you create and share user made content. This content can be pictures, placemarks, or virtual tours of various geographic places. Students in my class have created self running virtual tours of geologic stops in Chippewa County and Wisconsin, complete with pictures, information and video. Some teachers have used Google Earth to create a birthplace of famous authors tour, a map of key civil war battles, and a map with the most dangerous volcanoes around the world. Another powerful feature of Google Earth is the ability to download map overlays from other websites. USGS has a downloadable overlay of current earthquakes around the world http://earthquake.usgs.gov/, NOAA allows users to download cloud cover data http://wdssii.nssl.noaa.gov/geotiff_new/, and NASA http://neo.sci.gsfc.nasa.gov/has all of their scientific data related to climate ready to be used in Google Earth.
For more information check out the Google earth website or you can visit these links below for more examples or overlays.
