With a stunning combination of the GPS technology with ASP.net, AJAX and map services, EnGraph has come up with this really cool project.
Its basically about locating people where they are by using a GPS link and then updating it real time on a web site.
The demo tracks Tim Hibbard from Kansas to
Florida (A correction - it was South Kansas.) and also offers some other cool features like Getting his current whether information, getting the directions to reach him.
Check it out for yourself here - http://www.timhibbard.com/wherestim/
Some real good description of the technology follows here.