Printed Cycling maps are available for free in bicycle shops, at the NYC Department of City Planning bookstore at 22 Reade Street, NY, NY, 10007, libraries, and schools. They can also be obtained by calling the New York City Call Center at 311. Outside New York City, call 212-NEWYORK (639-9675). More info from the Department of City Planning.
UPDATE April 2016: The new 2016 Bike Map is out. Pick one up at your local bike shop or call 311.
An archive of NYC Bike Maps in PDF form is available going back to 1997