A Walk Through Rocinha
On one of my first days in Rio, I took a walk through Rocinha (Pronounced with an "H" at the beginning, not "R"). It was a great little tour since it was guided by a local photographer from Rocinha. Unfortunately, he didn't speak a word of English, so it was a good thing Harry was there.
Rocinha is the largest favela in Brazil. It's a huge shanty town in the mountains and it has a weird mix: a third world feel with lcd screens and satellite dishes. Once in a while you bump into a photographer or tourist group, but for the most part you're just navigating through the endless stairs and passageways. I felt like I was in the Labyrinth. Dance Magic Dance... hahahah.
If you are "afraid" of the favelas, there are guided professional tours. But, I highly recommend getting a small group or a local to show you around. When I ran into a big group it looked like people were performing for them and selling things as they went. I don't think you'll get the real deal.
If you want an idea of the elevation changes and the path I walked check this Nike+ map out. And this one too.
If you want to go alone, jump on one of the vans and ask if they go to Rocinha! Cheap and it takes about 30-40 minutes from Rio.
UPDATE: Here's a link to Levi's Studio on Facebook. He's the guy who gave us the tour!