Have you seen the one that plots crimes as if they were elevation? http://dougmccune.com/blog/2010/06/05/if-san-francisco-crime...
from wikipedia:
"Bayview-Hunters Point is predominantly African-American. The neighborhood has a population of 20,322 and is roughly 60% African-American, the highest concentration of that ethnic group in San Francisco."
The article on the community is quite lengthy and interesting:
http://en.wikipedia.org/wiki/Bayview-Hunters_Point,_San_Fran...
I've never lived in San Francisco and don't know whether this community has a bad rep. because it's mostly black or if it really is as crime-ridden as its reputation.
I think we can all agree that this kind of data analysis is really important though, to understand where we live and shape public policy.
That and the gentrification resulting from UCSF's push into the area...