Justin Kan and Emmett Shear watched their first startup, an online calendar called Kiko, implode when Google decided to do the same thing in 2006. They sold Kiko's scraps on eBay for $258,000 and wondered what to do with their lives. So the pair did the only thing they could think of: They went to see Paul Graham at his house in Cambridge, Mass., near Harvard Square. Graham sat them down and helped bang out a plan to create Justin.tv, now the Web's biggest portal for live video, with 31 million users a month and staked with $7.2 million of venture capital.Justin.tv is hardly the first, nor the...