2 of 7

April 8, 2011, New York City: Foursquare has redefined what it means to "check in." More than 8 million Foursquare members worldwide use the two-year-old company's free mobile app to broadcast their location on social networks like Facebook and Twitter. In exchange, members get loyalty rewards or special offers from businesses. Foursquare doesn't charge merchants to use its platform -- yet. But with 500 million check-ins over the past year alone, Foursquare has already attracted partners like American Express and Starbucks. Is the Fortune 500 in its future?

Left to right: Bryce Roberts, managing director, O'Reilly AlphaTech Ventures; Ben Horowitz, partner, Andreessen Horowitz; Dennis Crowley, co-founder and CEO, Foursquare; Naveen Selvadurai, co-founder, Foursquare; Albert Wenger, partner, Union Square Ventures

NEXT: Yum Brands
Last updated May 24 2011: 6:41 PM ET
Top 50 Wal-Mart holds Exxon Mobil at bay and rules the Fortune 500 for the second year in a row. Which other companies made the top 50? More
They're hiring! These Fortune 100 employers have at least 350 openings each, totaling more than 96,000 jobs. What are they looking for in a new hire? More
Best big companies to work for See the 27 companies that made both the Fortune 500 and Best Companies to Work For lists this year. More
Market indexes are shown in real time, except for the DJIA, which is delayed by two minutes. All times are ET. Disclaimer Morningstar: © 2014 Morningstar, Inc. All Rights Reserved. Disclaimer The Dow Jones IndexesSM are proprietary to and distributed by Dow Jones & Company, Inc. and have been licensed for use. All content of the Dow Jones IndexesSM © 2014 is proprietary to Dow Jones & Company, Inc. Chicago Mercantile Association. The market data is the property of Chicago Mercantile Exchange Inc. and its licensors. All rights reserved. FactSet Research Systems Inc. 2014. All rights reserved. Most stock quote data provided by BATS.