• by Gavin O'Malley  @mp_gavin, December 9, 2009

Location-based social network Gowalla has raised $8.4 million in a second round of funding led by Greylock Partners.

Founded in 2007, Austin, Texas-based Gowalla is among a growing number of location-based networks, which rely on virtual rewards and other various game-play elements to drive community involvement.

"It's exciting to discover new places and earn stamps for your passport from places as diverse as Buckingham Palace and the Sydney Opera House," said says Greylock's David Thacker, who has joined Gowalla's board of directors as part of this investment.

The new capital will be used to support the private company's growth, said Josh Williams, co-founder and CEO of Gowalla. "We believe there is a bright future for location-based applications," he said.

In the ten weeks since Gowalla officially launched its service on the iPhone and Android phones, 50,000 users have joined the service. During that period, its community has created and checked in at 150,000 locations in over 8,500 cities representing 100 countries around the world. Gowalla is now seeing more than 20,000 check-ins daily, and its users are adding new locations at a rate of 3,500 or more each day.

Rivals include Foursquare, which was founded by Dennis Crowley, who previously co-founded Dodgeball -- a similar service that was acquired by Google in mid-2005, and then closed down earlier this year.

Then there is Stalqer -- a curiously named location-based social network that has been described as "Foursquare on steroids." Similar to Foursquare, the free iPhone app tracks a user and their friends' locations and broadcasts the data through the application, and through push notifications. A key differentiator, however, is that Stalqer updates the location in the "background." In other words, Stalqer records users' location without them having to actually open up the application.

Gowalla has now raised over $10 million. New investors joining this latest round include Shasta Ventures, Maples Investments, Ron Conway, Kevin Rose, Gary Vaynerchuk, Shervin Pishevar, Jason Calacanis and Chris Sacca. Existing investors Alsop-Louie Partners and Founders Fund also participated in the round.

Greylock's Thacker works out of Greylock's Silicon Valley office, where he invests in consumer Internet and enterprise software ventures and advises several Greylock companies including Auditude, Oodle, Pandora and Redfin.