The Good, The Bad & The Empty from the Center for Urban Pedagogy on Vimeo.
Urban Design Lab's report The Potential for Urban Agriculture in New York City, which contains a series of interesting maps regarding vacant lots public and private in all five boroughs.
New Yorkers for Parks, formerly The Park Association of NYC, published a booklet in 1969 geniusly titled A Little About Lots. With their permission, we're making it available here as a PDF. It's a nice primer on making things happen in public and private land in any city. There are some parts that we wouldn't recommend following to the letter (for one, growing vegetables in the soil!), but we appreciate that the first chapter, "Getting People Together to Help", focuses on organizing communities.