Web advertising network Longboard Media says it has raised $6 million in a financing round, the company’s first.

Former eBay Inc. executives and Longboard Media founders Jim Barkow and Scott Engler say the ad network delivered three billion paid impressions in the 2010 holiday season and increased its publisher base by more than 40% in 2011. Longboard sells advertising that appears on the sites of such web retailers as Overstock.com Inc., No. 27 in Internet Retailer’s Top 500 Guide, and of comparison shopping engines ShopSavvy, Become.com and Shop.com.

The company says it will use the capital to expand its staff and invest in new technology.

“We have invested heavily in our publisher partners and deeply understand their needs, having spent our entire careers working to enhance online commerce businesses,” says Barkow. “Most retailers know they can no longer ignore the strategic and financial value of on-site advertising programs.  We realized the power of this format at eBay and established Longboard to enable large retailers and other in the commerce value chain to unlock this value in their businesses.”

Level Equity led the funding round. “We were impressed with every aspect of Longboard Media’s business and the size and rapid adoption in their market,” says George McCulloch, a partner at Level Equity.  “Scott and Jim bring deep experience in this market and have built a best-in-class offering, enabling retailers to unlock significant value in their largest asset.”