Two great documentaries came out this past year (2005) that are similar, while at the same time completly different.
Rize directed by famous photographer David LaChapelle tells the story of the dancing of the South Central area of Los Angeles. The movie tells the story behind the dance styles of Clowning and it's off shoot Krumping. The movie shows tons of the dancing and helps explain where this came from, how it adds value to the youth of a poor community protecting them largely from gangs and drugs.
Mad Hot Ballroom also involves dancing as well, but deals with 5th graders in New York Public Schools who take a a few months to learn classic dance styles like the Tango, Swing, etc. And then compete. Like Rize, the children are very poor and face rough life's where gangs and drugs are an obvious part of their culture. In Mad Hot Ballroom the kids also discuss issues of their future, and relationships with the opposite gender.
Both these movies show how dancing can be a very positive factor, and I think more than anything the kids in the impoverished area find value in life in being a part of something, whether that is the elementary dance competition (which is amazing) or if they're learning movies at Tommy the Clowns hip hop studio.
I loved both these movies, there both sad & moving, there both also encouraging and help give a perspective and create high energy emotion as you get a window into some crazy worlds we know nothing about.