Yelp

Credit the flu for the start of Yelp—when cofounder ­Jeremy Stoppelman couldn’t find good suggestions for local doctors online to cure his illness, he got to work on a site that would review and rate nearby businesses. What started as a simple email of referrals has become a go-to service for finding and giving feedback on local businesses in 219 cities spread across 32 countries. The San Francisco–based company has translated the 135 million reviews on its site and mobile app into dollars. Its net revenues jumped 30% last year to $713.1 million. What’s key now is to ­expand Yelp into new tech like wearables and to monetize its data through programs like Yelp Knowledge, which uses analytics to give brands sophisticated feedback.