CNN has an interesting video piece on Jason Polan. Jason is the author of the online blog Every Person in New York, a project that he describes as "... trying to draw every person in New York...drawing people everyday and posting as frequently as I can. It is possible that I will draw you without you knowing it. I draw in Subway stations and museums and restaurants and on street corners. I try not to be in the way when I am drawing or be too noticeable. Whenever I have a new batch of drawings I will post them on this blog."
An interesting study in observational research.