Forgive a shameless plug for a dear friend, but Harmon Parker builds footbridges in the back country around Kenya. His bridges bring people together and save lives:

http://www.bridgingthegapafrica.org/

What he does is not too different from the rope guy in the parable. He doesn't come in with a big team and a grand plan. He goes out and gets to know the people and finds out from them where they have dangerous crossings and what they need, and they build a bridge with him.

Harmon has the engineering know-how to make it safe, and the local people have knowledge he never could assume. When it's done, it's their bridge and they know how to maintain it: the people who use the bridge have been involved from the beginning.