Homicide: A Year on the Killing Streets is a book by David Simon and it is essentially an ethnography of the homicide unit of the Baltimore police department. I've read parts of it and it's very good. It's the book on which the TV show, The Wire is based on. The Wire also has excellent ethnographic elements.
Hanson calls for ethnography recommendations, and lukeprog seconds.
XFrequentist thirds.
Hivemind?