Part of the fun of watching aircraft at SNA is being able to see and hear the whole operation;  the activity at the airport is a great technological ballet conducted primarily by the control tower.  Being able to hear the aircraft pilots and the controller in the tower adds quite a bit to the airport experience.

John Wayne Airport Air Traffic Control Frequencies:

Tower: 126.8 and 379.9
Ground Control: 120.8
Clearance Delivery: 118.0 and 121.85
Southern California Approach Control: 121.3 and 263.1

Many people listen to air traffic control on VHF scanners that cost a couple of hundred dollars, and this is certainly the best way.  But if you are very short of cash (like me), you can get a very inexpensive VHF receiver at Radio Shack.  I picked up the Jetstream AM/FM/AIR radio for about $20  (Catalog number 12-615)

The receiver isn't very strong, so you have to be pretty close to an aircraft or airport to hear any air traffic control, but at the airport itself, the tower should come in very clearly.  I set up the radio when I get to the airport, and then turn the dial (which has no numbers or frequencies on it) until I can hear the ATIS comming in clearly.  (The ATIS is a recording that plays over and over telling aircraft the weather and other conditions at the airport.  You'll hear something like, "This is information bravo for John Wayne Airport.")  The tower is right next to that.

You can also listen to the SNA tower via the web using Real Audio.

If you listen carefully, you'll hear the tower controller coordinating all of the movements of all the aircraft at and around the airport.  You'll often also hear information about arriving aircraft (like the type of aircraft, airline, and distance from the airport) long before the aircraft come into view.

To hear and learn more about air traffic control towers, visit the Virtual Aircraft Tower or the CyberAir Airpark Tower.