For the past few days, Southwest Airlines has put a different destination on sale at 50% off, using a special promo code. Today it's Albuquerque.
We're surprised that all airlines aren't doing this more often. Actually, Alaska has been putting a different city on sale at 30% off, over the last several days, and JetBlue had some site-only sales at steep discounts, last week.
Clearly, if every airline did this, and only sold the promo code fares on their own web sites, it would change the face of the fare comparison/search industry. We, of course, would be fine with it.