The Lower East Side Business Improvement District, a nonprofit economic development organization that promotes improvements to the quality of life on the Lower East Side, offers great interactive maps. The organization also provides historical information about the area and walking tours. Visit http://www.lowereastsideny.com/explore/interactive-map/ to view all of their maps.
VanDam, Inc., http://www.vandam.com, is another great map resource for viewing New York City locations. Below is a sample of one of its isometric pocket maps.
Google Maps is a service that provides map, satellite, and street views of an area. Users can research exact addresses, plot lines and markers, and research buildings and local businesses. You can also customize and save maps for personal use. To see a map that documents my family history, click on this link.