Thanks to Tom, I've found a new service for getting flight information. Their data source is the air traffic control network.
Go to Flight Explorer and type in the flight number in the box in the lower left hand corner and you'll get all of the flight data you'll ever need (Note:once Mr. Ashcroft finds out about this, it will undoubtedly be shut down due to the possibility that you could use it to guide a home-built missile at an airplane with it...).
If you have a PC (or VirtualPC on a Mac), you can also get their service to provide real-time air traffic maps. Very cool.