John Keefe of WNYC made this pretty (and pretty addictive) map of New York City by income. See which neighborhoods are the richest (the Upper East Side) and the poorest (the South Bronx). Average income for each census track is listed in the interactive version.
And more interestingly see how close the very wealthy live to the very poor in some parts of the city (Brooklyn).
(Full map and article at WNYC)