Yovanno will replace Gigya co-founder and CEO Eyal Magen, who will become chief strategy officer, and will continue as general manager of Israeli operations for the Palo Alto, Calif.-based company.

"David's rare combination of experience building and scaling an advertising-based business and a passion for content and advertising technologies made him our absolute first choice for the position," said Magen in a statement.

Founded in 2006, Gigya has grown quickly to become the largest widget distribution network, with 174 million unique viewers worldwide in August, according to comScore's Widget Metrix report.

Its rapid expansion has attracted $23.5 million in venture backing to date, including an $11 million funding round led by DAG Ventures earlier this month.

The promise of Gigya's business model also lured Yovanno, who rose to chief operating officer for U.S. Media during eight years at ValueClick. "I believe in what's happening with the sharing of content on the Web," he said. He was also impressed at how Gigya "in a short time has been able to get amazing adoption, especially on the publisher side."

Yovanno departs ValueClick at a difficult time for the company as the souring economy erodes online display advertising, which accounts for almost 45% of its media business. The company's largest division also includes lead generation and e-mail marketing.

With ValueClick reporting third-quarter results Wednesday, equity analysts have recently lowered earnings estimates and price targets for the company. In an Oct. 20 research note, RBC Capital analyst Ross Sandler predicts that ValueClick's media business could be down 5% or more in 2009 because of display ad weakness.

ValueClick's stock closed Friday at $6.38 a share, down from about $25 a year ago.

The company disclosed Yovanno's impending departure in an Oct. 9 securities filing. It also said that Bill Todd, formerly senior vice president of sales for ValueClick Media, had been promoted to general manager of ValueClick Media.

In addition to being intrigued by the opportunity at Gigya, Yovanno said his tenure at ValueClick left him open to a new challenge. "I was at ValueClick for almost nine years," he said. "At some point, you've got to be ready for a change."

Among his priorities at Gigya will be building up sales efforts and bringing more advertisers on board. Brands including Toyota, Nike and Sprint have already run campaigns tapping into the company's widget network.

In particular, he wants to get advertisers to use Gigya's platform to plug into social media. Earlier this month, the company introduced a new service--Gigya Socialize--that lets Web sites add social networking features such as the ability to invite friends and keep up with them through a newsfeed.

Gigya's underlying Wildfire technology promotes viral distribution by allowing users to grab and share widgets via social networks such as MySpace and Facebook, blogs and e-mail. It also lets companies track widget usage.

EMarketer predicts that advertisers will spend $40 million in widget and applications this year--up from just $15 million last year. But that's still a tiny sliver of the more than $20 billion expected in online advertising this year.

"We're still at early stage of unlocking the ad component of this," said Yovanno.

This news story is important. I recommend that everyone read it.