Home for 96-year-old Arthur Darwin is this 14-by-16 shack on Posseum Key, a tiny island in the heart of a watery wilderness inside Everglades National Park, Fla. He cut the blocks himself for the one room concrete building where he lives his hermit existence. The windows have no glass, only screens and wooden shutters. He has no electricity or running water, "just the rain." He goes to bed when it gets dark and rises with the sun. But -- there's no ringing phone and no stack of bills.