Kami no ko tachi (2002)
It's in Japanese without subtitles (I'd love to see someone post a subtitled version), but the images are so strong (especially in part one) that you don't need to understand it all. Incredible footage of garbage pickers and the shantytown they live in. Safe for work, though it does contain some graphic images that might not be for the squeamish. In English it seems to be known as God's Children and it has apparently been shown in this country, but there doesn't seem to be any US DVD.
And a lot of the world lives like this.