@asap, check out http://greatergoodstudio.com/ here in Chicago in Logan Square. They’ve done projects with school lunch programs and public transportation among others. I briefly had them as professors at SAIC.
I actually first got into ID with a humanitarian focus in mind. This was about the time when Cooper Hewitt’s Design for the Other 90% hit the scene. It’s quite inspiring stuff.
There’s also Project H, not sure if they were mentioned before. The woman who started it is an SAIC grad as well.