Urban historian Steven Duncan and videographer Andrew Wonder journey into the tunnels underneath New York City in the fascinating and aptly-named Undercity, a 30-minute short shot on a Canon 5D in the city's subway tunnels, sewers, and abandoned subway stations (and on the Williamsburg bridge). Undercity is a highlight of recent DSLR projects, as the small size and low-light capability of these cameras enable this video to be made at all (most of the filming seen here is illegal). The short also includes interviews with the people you might not encounter during a visit to the city: residents of the tunnels themselves. Highly recommended.
Shot on a Canon 5D Mark II with a Canon 24 f/1.4 lens, with the Zacuto Rapid Fire, Zoom H4N and a Sennheiser G2 Wireless Lav (since replaced by the newer G3 series, though I also shoot with a G2). More about the project at Undercity.org, NYTimes, and NPR.