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Gregg Brockway has launched major brands that address chronic problems in the travel sector. But it was the pain of moving house that led the co-founder of Hotwire and TripIt to tackle his latest venture. "We moved several times," Brockway says. "Each time we moved, we would have furniture that just didn't fit in our new house, and it was driving me crazy. My wife had spent a lot of time finding those [pieces], picking out the colors, the fabrics, and then we'd basically give it away or sell that thing on Craigslist or to a consignment shop."

So Brockway launched Chairish, an online consigment shop for quality vintage furniture and home décor, along with his wife, Anna; former Hotwire partner Eric Grosse; and former TripIt partner Andy Denmark. "It was an idea that we had from personal experience [and] the pain around it," Brockway says.

The idea paid off quickly. "On the very first day, we actually sold some of that stuff without any marketing … and the smallest amount of traffic you can imagine," he says. "We were just, "Wow. We're on to something.'"