"The good relationships and alliances you create define your mutual ability to be effective," says Reid Hoffman, which is a fancy way of saying that friends really matter. Hoffman, 42, is a powerful friend to have. In the early aughts, the founding PayPaller established himself as one of Web 2.0's most influential angel investors, funding and coaching a bevy of once unknown startups (Facebook, Digg, Flickr, Zynga). He steered his own brainchild, LinkedIn, to profitability by embracing the trend of building the Brand Called You. "People need to run their careers like real businesses," he says. Hoffman, a whirling dervish of connecting, coaching, and philanthropy—he agreed to advise the microlender Kiva after hearing a parking-lot pitch—routinely dazzles friends with his progressive views. Now, as a VC at Greylock, he seeks entrepreneurs who are smart and energetic, with scalable ideas. "I want to know that they care about people more broadly than themselves," he says. "How do we make the world a better place by having been there?"