I like that Maranatha's volunteers cover their own travel costs, so a donated dollar goes almost entirely toward materials and labor rather than overhead. It's a model that rewards people willing to give both time and money, and it seems to stretch donations further because of it.
What sticks with me most is how physical the outcome is. A church, a school, a well — these are things a community can point to for decades afterward, which is a different kind of lasting impact than most one-time gifts provide, and a nice thing to have in mind heading into a season when giving is on a lot of people's minds anyway.