GVSHP (Greenwich Village Society for Historic Preservation) or Landmark West (on the Upper West Side) would have to be formed. These groups organize meetings, email blast, make phone calls and rally at local community boards along with sending letters to the Landmarks Preservation Commission of New York City. GVSHP has thousands of members including some local celebrities and they have a political clout that is missing in many of smaller committees of the local community boards.
So if anyone out there is great at social media and wants to start up a non-profit for preservation in Harlem, then this is the way to go. Set up a website and Facebook presence, have email updates to members about endangered buildings, have local friends and families join, start showing up at community board meetings in large numbers, write letters to local politicians and procure a strong relationship with LPC. Strength in numbers is more effective working on these types of community issues and an organization such as this will have more political muscle than a random letter from a concerned citizen (notable or otherwise) Anyone up for the challenge?