While checking around at to see what's new, I saw a link for this page passur. From their page you can view certain airports in quasi-realtime, watching as planes take off or land (it's delayed 10 minutes for security.) You can look at different ranges, from 4 miles to 90 miles, and see all the airplanes in the area, their height and type of aircraft. They even have a "replay" button that shows past days worth of flights.