Ask HN: Are there Open Source projects helping impoverished communities?

Hey Folks! Just had an interesting idea, inspired by http://kpcbfellows.com/build-for-good/challenges. I think it would be valuable to have a public list or repository of open challenges/projects that would allow the Open Source community to work on things that have a tangible effect on people's lives in struggling communities. IE building a farming plot mobile app that would help farmers in the 3rd world accurately and efficiently grow crops and improve their economy. I feel like having a compiled, growing list of these projects would give people who want to work on similar projects a hub to go to.