After selling their first small business and shuttering their second, former college roommates Niraj Shah and Steve Conine thought about getting "normal" jobs. But in the early 2000s, they stumbled across an unexpected trend: people were buying furniture online to get a wider selection. Within a few years, Niraj and Steve launched 250 different websites, selling everything from barstools to birdhouses. Eventually, they consolidated these sites into one giant brand: Wayfair. The company now carries more than 10 million items for home and last year brought in more than $4 billion in sales. Plus, for our postscript "How You Built That," how Carin Luna-Ostaseski fell in love with scotch and became the first American woman to create a Scotch whisky company.