Peter Fenton

For users of computers and mobile phones in big U.S. cities, Yelp has become a popular Web site for ranting, raving or just reading about local businesses, from the auto mechanic to the neighborhood bar.

Built almost entirely on five million reviews by zealous volunteers, the five-year-old San Francisco company shows how the Internet can amplify the voices of individuals to provide useful information to the community.

Matt Cohler, a pivotal player in Facebook Inc.'s rapid growth, is departing the popular online hangout to find other promising Internet startups for a prominent venture capital firm.

Cohler will remain Facebook's vice president of product management through the summer and then become a general partner at Benchmark Capital, according to a Thursday announcement.

Even after joining Benchmark, Cohler will remain a "special adviser" to Facebook's 24-year-old founder and chief executive, Mark Zuckerberg.