Google has been working in the favelas of Brazil to produce a virtual fieldtrip experience which, with the Olympics about to start in earnest (some events have already started) is well worth taking a look at. Thanks to Ben Hennig for the tipoff to this resource.
Favelas are being mapped because "a big part of having an identity is having an atlas".
They are not just a place, they are a people, and to fully understand them, you must go inside...
This is colourful and is well worth experiencing (make sure that you wear your headphones when you do)