United Airlines has some really low unadvertised fares from their competitor's hub airports.  Fares range from $122-$158 before tax and are valid for a 330-day travel period, 7 days a week.  However, not every travel day will be available at these amazing fares and summer dates are extremely scarce or not available at all depending on the route.  Nevertheless, you can get a great price if you buy now.  These fares are unadvertised and will not last very long at all.  They could be gone in just a few hours.  Tickets require a 7-day advance purchase.

Sample fares include: (Also available in reverse direction)

New York to Miami $128 round-trip

Dallas to New York $128 round-trip

Atlanta to Los Angeles $122 round-trip

San Francisco to Atlanta $122 round-trip

Detroit to San Francisco $122 round-trip

Providence to Las Vegas $158 round-trip

Minneapolis to Los Angeles $122 round-trip

Baltimore to Austin $158 round-trip

New York to Vail $128 round-trip

Baltimore to San Diego $158 round-trip

Memphis to San Francisco $122 round-trip

Flint to Orlando $158 round-trip