A while ago, I've posted some of Bill Rankin's maps on segregation for different cities in the USA. Those maps got a lot public attention because they were innovative in the way they depicted racial segregation by representing each individual as one single dot and each ethnicity as a different color. Needless to say this approach gives a much better visual effect than traditional choropleth maps.
Inspired in Rankin's map, Nicolau de Gusmão (geography student from Sao Paulo) has created in a racial dot map of Rio. Pretty neat. He used data from the 2010 population census and he created the map using QGIS. His post is written in Portuguese, but you don't need to speak the language to appreciate the maps and get your own conclusion about segregation levels in Rio.