One of the best examples of this is the Harlem Children's Zone. It's unreal what they're doing, and the impact that it's having on people over there. I'll let this segment from 60 Minutes explain more (this is the first part):
The man who started this program, Geoffrey Canada, was also featured on This American Life. The website for the program is here.
Anyway, what's really cool is this documentary that's coming out that will be tackling this topic. Check it out:
The movie looks like it is going to be a very high quality film. Go here to see the website for the film. Something really cool that some people associated with the film are doing is a pledge system, where once they reach 50,000 pledges from people to see the movie, the foundation will donate 250,000 new books to struggling schools across the country.