Perhaps the most interesting thing I've seen all day: A color-coded map of the Los Angeles area based on race and ethnicity, which has been making the rounds all day on Twitter and via several local blogs (and now, finally, this one).
The map is the work of Eric Fischer, who explains it thus on Flickr:
I was astounded by Bill Rankin's map of Chicago's racial and ethnic divides and wanted to see what other cities looked like mapped the same way. To match his map, Red is White, Blue is Black, Green is Asian, Orange is Hispanic, Gray is Other, and each dot is 25 people. Data from Census 2000.
Rankin's work can be found on the website Radical Cartography. More of Fischer's work, including more maps, can be found on his Flickr photostream.