I've posted an article that shows how to create an Google Earth KML file by writing to the response stream. The code is for this page:
http://timhibbard.com/demo/kml.aspx
That page creates a KML file that show Memorial Stadium in Google Earth.
The code also shows how to use query strings to create a KML file for any location like this page:
http://www.timhibbard.com/demo/kml.aspx?lat=39.0485&lon=-94.484&icon=http://timhibbard.com/images/chiefs_icon.jpg
Arrowhead Stadium in Kansas City.
Read the article for more information:
http://geekswithblogs.net/thibbard/articles/92625.aspx