COMPUTER DIRECT MARKETER Global DirectMail Corp., based in Port Washington, NY, has struck deals with American, Delta and United airlines that will allow it to introduce what it claims to be one of the first frequent flyer incentive programs for the online purchase of personal computers and related products. The program will be offered through Global’s e-commerce Web site (www.dartek.com). Global DirectMail said that dartek.com had been testing the online Frequent Buyer’s Club over the last several months.