This is just way too cool. If you have the Google Earth application installed on your PC, there are some interesting 'add-ons' you can use with it. Examples include US chart overlays, air traffic at some Class Bravo airports, and a 3D representation of the US airspace. Below is what I am looking at right now, with the 3D blocks and Boston traffic enabled. Then I have the liveatc Boston Approach feed running in the background for the full picture.
Make sure to use the 'tilt' feature. Have fun!
Find it all here: http://www.fboweb.com/antest/ge/intro.aspx