Get valuable air miles for holiday purchases. Now you can convert any credit card in your wallet into an air mileage reward card.  United Airlines and Delta Airlines have launched a new program that enables you to register up to three different credit cards that will earn up to five miles for each dollar charged at selected merchants. Participating merchants include Eddie Bauer, The Sharper Image, Spiegel, Jos. A Bank, Cushman Fruit Company, Computability, Vitamins.com, CertificateXpress.com, ClubComputer.com and more. The United Mileage Plus Shopping program is currently awarding a 1,000 mile bonus to consumers who make two separate purchases from participating merchants within 60 days of enrolling. United also awards a 100 mile bonus just for signing up. Delta SkyMiles Shopping offers a 100 signing bonus only. For more information for United's Mileage Plus Shopping program, call 888-581-9575 or visit www.ual.com; for Delta's SkyMiles Shopping, call 800-405-4223 or visit www.SkyMilesShopping.com .