Ask HN: What apps would help individuals in high need or catastrophic events?

Thinking in technology and events like the Nepal's Earthquake, California fires, flooding and other catastrophic events. What apps do we have to help on that? All of them are aimed to optimize help arranged by organizations or governments? Wouldn't make sense that we use technology to optimize individual-to-individual help? Maybe this would be important beyond catastrophes and with small easy actions help improve life of people or families in really bad situations who's life would radically improve if one guy in one side of the world decides buy for them a gravitylight (https://www.youtube.com/watch?v=QX32yQgybaw) or a water filter (http://inhabitat.com/6-water-purifying-devices-for-clean-drinking-water-in-the-developing-world/), mentoring or a modest P2P lending. What social network or apps do we have to connect and optimize individual-to-individual help?