here is the trailer to FAVELA RISING:
http://favelarising.com/
Another very good film is 'CHOKA', about street kids in Zambia.
Here is a link:
http://www.familycare.org/network/f28.htm
Another very good doc by the same team who did Choka is called 'On The Frontline':
http://www.planetinfocus.org/onthefrontline
(The two above films I am a little bias about seeing as they are both set in Zambia)
And