the Rubicon Project, a company with a mission to automate the large, yet highly inefficient Internet advertising industry, has raised $21 million in total capital with a $15 million follow-on to the $6 million financing the company announced four months ago on October 8. The new Series B round was led by Mayfield Fund with participation from IDG Ventures Asia; Stanford University; University of California Berkeley; Matt Coffin, founder and former CEO of LowerMyBills.com and Clearstone Venture Partners, the company’s Series A investor.

The additional capital will fuel future business growth initiatives including international expansion, strategic acquisitions, research and development and infrastructure required to support the influx of websites signing up for the company’s new ad network optimization service.

In response to this growing problem, on October 8, 2007, the Rubicon Project announced a new service for websites to generate mad cash from the ads on their site by optimizing ad networks. Websites using the Rubicon Project solution have seen revenue increases ranging from 33% to 300%.

“There is no question this has been a burning problem for websites. In the twelve weeks since our launch, more than 3,000 websites have signed up and we have optimized more than 4 billion ads across 50 of the top ad networks,” said Frank Addante, CEO and Founder, the Rubicon Project.

the Rubicon Project is a group of industry-experienced, aggressive and passionate renegades dedicated to bringing a new level of efficiency to the fragmented Internet advertising space. The founders of the Rubicon Project shook up the online advertising industry in 1998 when they created L90/adMonitor, one of the most successful Internet advertising platforms that served over 3,000 of the web’s most recognized sites, reaching 65% of the Internet population before DoubleClick acquired it.