This one seems kind of obvious, but hey I haven't seen one yet. I also couldn't find one with google. So here ya go.
A NYC Subway Map for the SONY Playstation Portable (PSP.)
Fun, safe and crystal clear. (in fact you could even take the resolution down to save precious memory stick space.)
I am fairly sure I should say you may not use this map. It is not to be downloaded by clicking Here and dropped into a PHOTO folder on your PSP. It should also not be viewed using the magnifying glass (found when you push the triangle button.) And finally you should not use the Joystick to navigate thru the map.
Ok, that should satisfy the boys in legal.
UPDATE: This map was obtained from www.nycsubway.org and was designed by Michael Calcagno.