"Envisioning Development: What is Affordable Housing?" is an interactive Flash-based map of housing and income statistics on a neighborhood-by-neighborhood basis throughout the New York City area. Although I've seen similar statistical/analytical interactive maps with similar data plenty of times, the aesthetic design and information visualization "impact" of this map is almost breathtaking. This map is part of an online resource toolkit for urban planning and land use education based around NYC, offered by the Center for Urban Pedagogy.
Movesmart.org is a new website and nonprofit organization dedicated to helping housing seekers find neighborhoods that meet their needs while at the same time promoting diverse, healthy, and vibrant communities. The organization's core offering is an interactive mapping application called Neighborhood Finder (launching late summer 2009), which provides a geographic interface to many different types of data about neighborhoods. Other resources include a series of informative guides about relevant housing and neighborhood topics and a blog about fair housing and other similar issues.
You can learn more about Movesmart.org, as well as watch a short video about the organization and the website, by visiting http://movesmart.org/about (new window).