Promises comprehensive religious demographic figures for every county, state, and urban area in the United States, but unfortunately their data are probably not very accurate for a diverse immigrant city like New York
An extraordinary mapping tool developed by the New York Times. Maps a wide range of demographic data, from the Census Bureau's recent American Community Survey, all searchable down to individual census tracts. Zoom into any area, and click on "View More Maps" to pick a topic. It's social geography nerd heaven.
A map of city services, facilities, cultural landmarks and political institutions. Zoom into any area, the click on any of the features listed on the right to create an overlay on the basic map.
Better demographic figures than ARDA, but still not totally reliable for smaller faith communities. Also includes sophisticated survey research on religious beliefs and practices, and on social/political views.
Links to a wide range of contemporary and historical demographic maps. Their figures for religious affiliation (drawn from the same sources as the ARDA, above) are probably not very accurate for a diverse immigrant city like New York.