I just learned that free 1 year license for Google Earth Pro is available for qualified academic users. Send email to den@google.com requesting for a one page authorization document to use the software. Then, you can download the Googe images and work them with GIS software.
"A Boston company is giving away software that can turn nearly any laptop computer into a global positioning system, enabling users to find the nearest restaurant, hospital, or gas station at the touch of a button." (via Boston Globe, 3/23/06) You can download this software directly from LOKI
Following Google Earth and Google Moon , now Google Mars. "Google Mars doesn't provide driving directions, but users can see the planet in three different formats: The Martian elevation map is color-coded by altitude; the visible-imagery map shows the surface in black-and-white pictures; the infrared map indicates temperature, with cooler areas dark and warmer areas bright."(Souce: Google's New Frontier: Online Maps of Mars. /San Francisco Chronicle/, Mar. 14, p. D1. 2006).