In the aftermath of Hurricane Sandy, one thing is striking: the extent to which many of the best and first responders have been local. From Brooklyn down to the Jersey Shore, Sandy has left its mark. But now, stories abound of community groups shoveling sand out of living rooms, feeding and housing the homeless, and arranging online help through listservs and crowdfunding. Somehow, communities have married the best of old-fashioned neighborliness to 21st century networking — resulting in a steady flow of local energy against a sea of devastation.