NYC is divided into 59 community districts. Each district has a community board. It's useful to know your district because statistics are often presented on a district-level.
A list with contact and web address information for local community boards in all 5 boroughs. Community Board websites typically contain demographic and statistical data, in addition to constituent services. Not all community boards have websites.
Check out the neighborhood branch of the public library
Use the map to find branches in your neighborhood. Branch libraries often have information about the neighborhood they serve.
Community District Profiles
From the Department of City Planning, each profile contains land-use and demographic info for that district.
My Neighborhood Statistics
From NYC.gov, this site allows you to visualize land-use by searching a specific address.