"We're certainly not seeing a slowdown," Levinsohn told the audience Monday, during a morning keynote address at the OMMA conference in New York.

Yahoo CEO Terry Semel said last week that ad growth had slowed this month in the financial-services and automotive categories. The remarks sparked a wave of frenetic activity, as analysts and forecasters attempted to determine whether the slowdown was industry-wide or limited to Yahoo, which eMarketer says accounts for about 18 percent of the online ad market.

Levinsohn also was bullish about user-created content, arguing that media companies must offer consumers a way to participate. "We've been thinking a lot about platforms," he said. "If you don't build something today ... with consumer participation in mind, it's not going to go anywhere."

But while he was optimistic about online media, Levinsohn admitted that the Web presented significant challenges for advertisers. Users are spending more time than ever consuming media, but they're at so many sites, it's hard for marketers and media execs to find them, he added. "No one's ever had to deal with 20,000 sites before. It's so much easier to pick up the phone and call Yahoo."

He added that Fox Interactive's online properties, including entertainment site IGN.com and social networking site MySpace, now draw 131 million unique users. MySpace alone now has more than 100 million registered profiles.

Levinsohn also expressed hope for TV, newspapers and other traditional media--mainstays of Fox Interactive's parent company, News Corp. "Let's not put a nail in the coffin of television or radio or newspapers, because in our lifetime," he said, "they're not going anywhere."

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