As big premium hikes drive its core health-insurance business, UnitedHealth is also striking it rich with smart innovations. A new MasterCard will double as a United Health membership card, allowing members to tap into flexible benefit plans to pay for non-covered costs such as eyeglasses. Minnetonka (Minn.)-based UnitedHealth also serves up supplemental Medicare coverage, Medicaid services for state governments, and R&D-related drug- development services for drugmakers. Hefty margins of 6.3% helped hike profits by 35%. Matching that in 2004 may be tough.