Ask James Dolan what he'd call himself and he'll likely say, "musician." But the guitarist and singer in JD & The Straight Shot does a lot more than play 30 to 40 yearly gigs with his band, occasionally opening for the Eagles. Dolan, 59, is one of the most active (and sometimes polarizing) entertainment moguls in New York. He runs Cablevision Systems Corp., the country's eighth-largest cable and broadband provider, which was started by his father, Charles (who lives next door to James in Oyster Bay on Long Island), and has more than 3 million subscribers in the tristate area and 15,000 employees.