After 90 Meetings in 90 Days, These Founders Finally Found Their Customer After creating a potentially groundbreaking solution, two founders weren't sure whom to sell it to.

When Gil Addo's grandmother was diagnosed with a brain tumor in 1998, she traveled from her home in Barbados to Boston for surgery, where the best care was available. The treatment was a success, but for the next five years, she had to regularly repeat the exhausting trek north for post-op care from a medical specialist. Addo knew there had to be an easier way.

Related: The How-to: Figuring Out Who Your Customer Is

"Most medical specialists' expertise is centralized in big cities, and they're overbooked and costly," he says. "And almost half the reasons a patient goes to see a specialist could be handled by their primary care physician." So along with his co-founder, Carlos Reines, Addo created RubiconMD, a digital platform that allows primary care physicians to consult virtually with top medical specialists around the country within 24 hours.