""We Specialize in Access, Insight and Intelligence into the Defense Industry, DoD and Government programs," the Web site for a Cohen investment advisory service said until recently. The Web site said the Cohen Group's "Competitive Advantage" included "Senior level relationships throughout industry and government." One day Cohen is appearing at a Lockheed Martin Corp. event in India, smoothing the way for a fighter-jet sale; another, he's attending a charity ball at the request of a company that wants him at its table because, an executive at the company says, "You are judged by the friends you keep.""