Billionaire investor Jeff Bezos is putting $3 million behind San Francisco-based Kongregate, an online casual games site that draws its content from Indie developers.

The investment brings Kongregate’s investment total to $9 million, with a $1 million angel round and a $5 million investment by Greylock Partners, a backer of Red Hat, Digg and Facebook.

The investment by Bezos, founder and chief executive of Amazon.com, comes through his person investment fund, Bezos Expeditions.

Kongregate competes with companies like Miniclip in trying to build large audiences for casual games offered through an Internet browser. Kongregate, founded in June 2006, offers more than 4,000 Flash and Shockwave games from more than 1,500 developers.

Kongregate Chief Executive Jim Greer likened the "super-angel" funding round to an insurance policy.

“This is a rainy-day recession fund,” he said, noting that the company still has more than half of the previously raised $6 million in the bank.

“Jeff approached us about it,” he added. “We were on Amazon’s radar.”

Kongregate’s business plan calls for Chief Revenue Officer Lee Uniacke, a recent hire from publisher Ziff-Davis Media and a veteran of Viacom’s MTV Networks, to build up a sales force that can draw advertising to the site.

Within a few weeks, Kongregate also plans to begin releasing games on Facebook.

“Our hope is we reach a new audience there,” Mr. Greer said. “Some play on Facebook, some play on Kongregate.com. If you play a game on Kongregate.com, it will notify your friends on Facebook.”

Kongregate is the first game company to get an investment from Bezos Expeditions, whose portfolio companies include: 37 Signals, a Web applications company; Linden Lab, creator of the Second Life virtual world, and MFG.com, an online marketplace for manufacturers.