VATSIMThis is entirely fascinating: Virtual Planes, Virtual Airports And Absolutely No Rogering: Inside The Fascinating World Of VATSIM.
What is this, you ask, your eyes wide open with interest? Here's a description from the RPS article:
VATSIM is short for Virtual Air Traffic Simulation Network. It’s a system which populates a flight sim by connecting enthusiasts who each take on piloting or air traffic controller roles.
That's incredibly ambitious, and even more incredible, it's tremendously successful. So, for instance, you might fly from Chicago to New York, but instead of silence, you'd be hearing air traffic chatter for the duration of your flight.
It's all quite remarkable, and I'd never even heard of it today. Hit the article link and enjoy.