In the summer of 1985, Bob Geldof staged a dual-venue rock concert called “Live Aid” that changed the face of charity fundraising. A glittering lineup of rock stars and celebrities raised millions to feed starving children in Ethiopia, and established a model that would eventually aid victims of everything from hurricanes to Third World debt. But thirty years later, the Ice Bucket Challenge has scrambled fundraising paradigms, and raised a pressing question: how to turn social media into meaningful philanthropy?