Look at any Web site and you're bound to see one common attribute: white space. Most people completely ignore these unused spaces in the left and right margins. 

But David Parkinson -- the founder of emptyspaceads -- thinks there's opportunity to show advertisements in these underutilized areas. And he's not alone.

Second Avenue Partners' Nick Hanauer and Mike Slade -- two online advertising veterans - are backing the tiny Pioneer Square startup.

Emptyspaceads raised $500,000 in seed funding from Second Avenue last summer, and it is now looking to sign up publishers to test the system. Essentially, the company creates an ad unit that appears only when a user passes his or her mouse over the empty space in the left and right rails of a given site.

"We monetize an element of your Web page that no other company goes after: that white space," said Parkinson, who has filed for a patent on the idea. "And we believe there is a balance between monetizing that space and still letting it serve as the design aesthetic."

Parkinson said the company plugs in to existing ad networks from Google and Yahoo, making it relatively easy for publishers to serve a new type of ad to their readers.

"For us, we say, keep using everything you already using, but let us help you make more money by using real estate that you didn't even know you had," said the 25-year-old entrepreneur. "If you look at the top 300 ad networks, they are all battling over those top placements -- the leaderboards and the skyscrapers -- and we are going after that totally different area."

During the test period, emptyspaceads plans to give publishers 100 percent of the ad revenue it generates. Over time, it will take a small, yet-to-be-determined cut of the ads served through the service, Parkinson said. 

"We don't want to get paid unless we are adding advertising dollars to the bottom line," he said.

As a result of the investment, Second Avenue's Mike Slade joined the company's board. Slade is the former CEO of Starwave, while Hanauer previously founded online advertising giant aQuantive.

The company also recently tapped Bilal Aslam -- a former program manager at Microsoft -- as its vice president of engineering. Aslam signed on after looking at Web sites and discovering that many top sites devote as much as 40 percent of their design to empty space.

"Nothing is happening there, that's what sold me on it," said Aslam. "And that's where I saw the big idea."

Parkinson admits that emptyspaceads is a little unusual, but in early tests he said consumers clicked through the ads with higher frequency than traditional banner ads. That's in part because people tune out traditional ad placements, but also because the ads stand out when people move the mouse to the scroll bar on the right side of a Web page.

As monitors increase in size and clarity, Parkinson thinks the ads will become even more noticeable.

"It is one of these really big ideas. It is either going to really take off -- and we really believe that it will -- or it won't," he said.

At this point the compay has about 10 publishers using the service, including Daily Home Renvoation Tips and CareerCup.com. To be successful, Parkinson said they will need to attract some high-traffic Web sites in the top 100 or 1,000.

In this tough economy, Parkinson thinks he has a good story to tell online publishers that are looking for a little extra revenue.

"This economy, as bad as it is, is really good for us because it increases the desire to experiment with new, innovative advertising ideas," he said.

Emptyspaceads is offering a limited number of invites to TechFlash readers. If interested, go here.