First, this is a great thought. Gamification has been a theme of other challenges associated with behavior as well; we've also studied how positive feedback can help to encourage behavior change when the change is relatively low "cost" but has a high long-term benefit.
I also think it's great to be conscious of people's specific dietary needs. That being said, consumption of fresh produce is a good thing in virtually all cases! :) So I think that for the most part, providing positive feedback/incentives for consumption of fruit and veggies is a good thing. The MyFitnessPal app allows users to customize their daily goal based on dietary needs, and then rewards them for sticking to the goal they designed. That might be something to consider.
This actually reminded me of lending circles (see: http://www.bostonglobe.com/business/2015/01/13/community-lending-circles-mainstream/gkgoWoIlfTIS3z1bhkkjiP/story.html).
I wonder if something like this could be implemented with regard to higher education; the hurdle is that most alumni want to donate to their own schools/students of those schools. The problem, of course, is that it can create a feedback loop whereby the richest schools get the most funding. How could a lending network form that is less restrictive?
I agree that this is a great tool! My question, which Shane touched upon, is how something like this could be used to help more those who are more vulnerable and increase social mobility. For example: in Massachusetts, the only schools that qualify for the SoFi "MBA Loan" are Harvard and MIT. Of course, the challenge is that alumni want to give to their own schools, and that alumni of elite schools generally have more money to give. How could we build on this idea to direct support where it is most needed (e.g. low income, first-generation students, who are not at elite schools with generous aid packages)?