Google and Overture Search for Tomorrow

That number chiefly comprises pay-per-click listings revenue -- money that advertisers bid to be listed high in search results, which they pay only if Internet users click on their listing to visit their site -- but it also includes paid inclusion, advertiser payments for having their sites checked for possible inclusion in search listings ordered by relevance, not bid amount.

The Here's Why

Among the avenues for further growth are contextual advertising -- repurposing search engine ads for nonsearch-engine contextual pages. Google, for one, has started running these contextual ads from its search engine advertisers in the hopes, for example, that people reading a Web page devoted to rabbits are likely prospects for a pet food store.

Another possibility is locally targeted search-engine advertising -- a promising market, given the huge size of the yellow pages business, but one that has so far proved smaller than expected for ventures such as Microsoft's Sidewalk and USA Interactive's (USAI Quote) Citysearch.

Overture's chief technology officer, Paul Ryan, said that what the industry should be working for is "democratizing" other online marketing channels, the way that pay-per-click search opened up the Internet advertising door to numerous small businesses that wouldn't have been able to afford conventional brand advertising campaigns online. That means, he said, giving small advertisers similar tools to market through contextual advertising, local search, paid inclusion and email advertising.

But, he said, this outlook shouldn't be interpreted as a road map for Overture's business plans. "I think it's the goal for the industry," he said.