The website that I used to imagine a community engagement program is http://www.unicefusa.org. UNICEF "works in more than 190 countries and territories to save and improve children's lives, providing health care and immunizations, clean water and sanitation, nutrition, education, emergency relief and more."
My fun, large scale, idea is to design vatican sized UNICEF compounds in EVERY major city, which would host massive health care facilities, food stores, teachers, and every facility or personnel they would need.
The realistic idea would somewhat similar to their new app, where a sponsor helps provide clean water to children dependent on the length of time a user does not touch their mobile device. In my version, we would have to partner with FitBit or Nike+. For every 1,000 miles you walk, a sponsor donates $1 to UNICEF. This provides more incentive for people to exercise and passively donate money: because people would rather passively donate than actively.