With the launch of STS-134, Space Shuttle Endeavour's final flight to the International Space Station early last Monday morning before being retired from active service, Google Earth has released a free for download application that allows you to track Endeavour's position in orbit for its twelve day mission. I find it fascinating how far this civilian project has progressed technologically, something that I think we now take somewhat for granted.
http://www.nasa.gov/mission_pages/shuttle/shuttlemissions/shuttle_google_earth.html