Flight Radar 24 is so cool!

I rarely find a website that I find this cool, but here it is...www.flightradar24.com  What is it.  It allows you to track the flight of every airliner in America in real time.  You get a map, you have little planes moving across the landscape.  Click on a plane, it will tell you the Airline, flight number, departure and arrival and have a line showing you the flight pattern it has taken so far.  Note, to save resources, it does time out after 30 minutes, unless you have a paid account.