Step into the Los Angeles offices of the Rubicon Project and you might feel as if you've been transported to Silicon Valley, circa 1999. Dozens of 20-somethings crowd around tables in one big room, hunched over laptops, typing away. A few play a Nintendo Wii game in the corner. One sips a beer.

Step into the Los Angeles offices of the Rubicon Project and you might feel as if you've been transported to Silicon Valley, circa 1999. Dozens of 20-somethings crowd around tables in one big room, hunched over laptops, typing away. A few play a Nintendo Wii game in the corner. One sips a beer.

Investors may be jittery about the current economy, but Rubicon — a startup online advertising company — isn't worried. It hired most of its 37 employees in the past few months, and it planned to announce that it has received a new round of funding, bringing its total to $21 million in eight months.

"Right now, companies are understanding that digital media is a viable business," said Daniel Taylor, an analyst with the research firm Yankee Group. "It's like it is 1950 and someone just realized you can sell advertising on television."

Yankee Group predicts that the amount spent on online advertising in the United States will jump from $21.7 billion in 2007 to $50.3 billion in 2011. But the market isn't very effective right now, says Frank Addante, Rubicon's 31-year-old founder and CEO. There are more companies spending money online, but many of their ads end up on Web sites that aren't relevant to the product they're selling. Moreover, Addante says, Web sites "are not making as much money as they could be" from ads.

That's because on average, Web sites can sell only about 20 percent of their ad space directly to advertisers. They turn to ad networks — companies providing them with ads from partner companies — to fill the rest. But those networks don't always do a great job matching the spots to interested eyeballs.

Cue the Rubicon Project. Through complicated math, its service assesses in real time which ad networks will provide given Web sites with the most relevant ads, and sends ads from those networks. Web sites use this service to receive the ads that pay the best and those that are the most relevant to their readers, which are more likely to be clicked on.

That allows Web sites to "make mad cash" from advertising, as Addante likes to put it. The 3,000 Web sites that have signed up so far have seen revenue increases ranging from 33 percent to 300 percent, he says.

Rubicon makes online advertising more efficient and transparent, which will help attract even more dollars online, said Raj Kapoor, managing director of the Silicon Valley venture capital firm Mayfield Fund, one of Rubicon's investors.

The success of advertising on media such as television, newspapers and radio is difficult to measure, Kapoor said, whereas online, everything can be tracked. Logically, he says, when advertisers have less money to spend, they'll want to put it where they can track it.

In a recession, Kapoor predicts, "overall, the budgets will go down, and the shift of what's left will go more toward the Internet."

Rubicon's team may be young, but it has a wealth of Internet experience. Before he was 30, Addante had started five companies: He took one public, sold two and moved one up to Silicon Valley. The other, he calls a "learning experience."

He founded Rubicon eight months ago. Also on the Rubicon team: Duc Chau, vice president of technology, who, as the lead developer of the initial MySpace community, had that site's first profile.

Kapoor says Rubicon is part of the growing tech community in Los Angeles, which has seen considerably more investment of late from Silicon Valley firms. That's especially true in the online advertising realm.

"The online advertising marketing is kicking off, and we think there's a lot of opportunities for disruptive startups to make their mark," Kapoor said.