Scott - Have you considered fusing religious networks with savings groups? Mission Asset Fund works with immigrants in the U.S. and their informal savings groups to successfully build assets and credit scores. What if we could extend the same model to people born in the U.S. who have similar needs?
The problem is that most Americans without an immigrant background are unfamiliar with the idea of savings groups. In fact, I think many would approach it with suspicion and distrust. A solution could be to introduce groups through existing religious networks where folks are already bound by beliefs/morals and social ties - and that, like you say, already create physical spaces for people to come together.
Like Nicole, I know of at least one church where I could see this type of program working. I've thought about it a lot and would be interested to talk more, maybe collaborate. Good luck. Be in touch!