NEW YORK (Reuters) - Tens of millions of East Coast residents scrambled on Sunday to prepare for Hurricane Sandy, which could make landfall as the largest storm to hit the United States, bringing battering winds, flooding and even heavy snow. The massive storm, which has already killed 66 people in the Caribbean, was headed toward a densely populated region that includes Washington, New York and Boston and its effects could be felt for hundreds of miles, officials warned. It could be the largest storm to hit the United States, according to the National Oceanic and Atmospheric Administration. ...