With 47,000 would-be marathoners with nothing to do tomorrow, many are tapping their pent-up energies to help out communities still recovering from Hurricane Sandy. One Facebook group (with 1,577 likes) is organizing a run in support of Staten Island tomorrow; 40 Dutch marathoners meanwhile have traveled over to ravaged Newark to help, according to mayor Cory Booker; and a new website, Race 2 Recover, offers marathon runners and their families a way to donate unused hotel rooms to victims of the storm.