Find out almost anything on Oasis Map
This is a fantastic and easy to use mapping program that gives enormous detail about the city:
http://www.oasisnyc.net/
Look up a Building
Department of Buildings
This is where you can search for general information on a property in the city including recorded complaints and violations, actions, applications, and inspections: http://a810-bisweb.nyc.gov/bisweb/bsqpm01.jsp
How to determine permit & owner status of properties
Navigate to http://a810-bisweb.nyc.gov/bisweb/bsqpm01.jsp
BIS menu: Option “A”, Building Information search. Input information for search of building (i.e. building number)
Zoning Information
Property Shark
(commercial site. Great use of all public building info. Register (free) and you get 10 daily / 50 monthly free searches.)