Delta Air Lines is offering a $50 American Express prepaid card for purchasing a flight between New York and Los Angeles, San Francisco, San Diego or Portland, Ore. at delta.com.To qualify for the offer, you will need to register and pay for your ticket with any American Express credit card. The offer is valid on roundtrip nonstop Delta flights only. If you purchase multiple flights on eligible routes, an additional $50 will be added to your prepaid Amex card for each roundtrip flight you book. All travel must be completed by June 30, 2008 and codeshare flights are not eligible. Visit http://insideflyerus.wpengine.com/link/?975