Jake Bronstein of Zoomdoogle published a free and fantastic guide of 314 fun things to do in New York City. He printed up and distributed a bunch of copies, and has also made it available as a PDF. I saved a copy on my iPad for the next time I visit.
Mark Frauenfelder is the founder of Boing Boing and the editor-in-chief of MAKE and Cool Tools. Twitter: @frauenfelder. Come and hear Mark speak at the ALA conference in Chicago on July 1.