You can certainly take a trip to Brazil and work as a volunteer in one of its favelas. There are operators that offer these kind of trips to not just Brazil. Though most are run as tours at a cost to you, alternative may be you move on down to Brazil well before the Olympic Games and get a job, easiest being to teach English. Provided you’ll learn some Portuguese you may be in a good position to find a volunteering position or even one with pay during the summer Olympic Games if not before. Similar opportunities existed in Beijing and are likely to be available in Rio de Janiero as well. We’ll keep you posted as we hear on the topic of jobs or volunteering openings for foreigners.