For Citymeals-on-Wheels, a nonprofit group that delivers food to homebound New Yorkers, the Wall Street crisis already means 100,000 fewer meals will be delivered to people who need them. After Citymeals-on-Wheels cut back its program, some elderly people began receiving one meal a day instead of two. "You know the next day you got a meal coming, so you don't have to worry, then all of a sudden it's not there," said Dorothy Skinner, 82, a retired special-education aide who lives alone in Manhattan. "It really hits you." Across New York, nonprofit organizations are anxiously tracking the demise of longtime donors such as Lehman Brothers, Merrill Lynch, American International Group and Bear Stearns, as Wall Street's problems begin to trickle down to the city's poorest residents.