Enterprise tech startups have been on a 12-month IPO joyride. From MongoDB to Dropbox to Eventbrite, more than 20 startups in the enterprise tech industry have sold shares to the public and made splashy Wall Street debuts this past year. Unlike consumer internet companies whose products are usually free and designed for the masses, these enterprise startups create products and service that are sold to other businesses. It's a massive $3.7 trillion worldwide market, and yet these startups don't always enjoy the mainstream name recognition of their consumer counterparts.