Statistics wunderkind Nate Silver in the New York Times:
It’s called “hidden-city ticketing,” but before I explain how to execute the maneuver, you’re going to need some background. Passengers flying to or from airports that are dominated by a single carrier — like Memphis, Newark or Dallas/Fort Worth — pay fares 20 or 30 percent higher than at non-hub airports. The prices are even more inflated when you’re flying from a smaller city with a limited number of flights. A nonstop one-way ticket from Des Moines to Dallas/Fort Worth is $375 on American Airlines, for example — more than the $335 Delta will charge you to fly from Miami to Anchorage.
But what happens when you’re interested in flying American from Des Moines to Los Angeles, which hosts a more competitive airport? That flight is only about half the price ($186), despite its being more than double the distance. Now, here’s the trick: American flights from Des Moines to L.A. have a layover in Dallas. If you want to travel to Dallas, the best way to get a reasonable fare is to book the flight to Los Angeles instead, and simply get off the plane at Dallas.