NEW YORK Media companies are still hungry. Is there much left for them to consume that they will find satisfying?

NBC Universal's $600 million acquisition of iVillage, an early Internet company catering to women, highlights the continuing interest by media companies in adding new Web sites to reach and connect with consumers, hobbyists, parents, investors, car buyers, Scrabble players and virtually every other niche audience.

To that end, digital-era media companies like Yahoo and Google, as well as traditional media companies, including those with deep roots in television and print, continue to scour the Internet for emerging content and technology companies. But the pickings of obvious acquisition candidates, while hardly exhausted, are slimming, according to financiers, entrepreneurs and industry analysts who follow the sector.

That leaves the media companies trying to figure out - as they did with far less discipline during the dot-com boom - which of the emerging generation of Web sites have lasting business models or, at least, can continue to build traffic. "There was a point last year where we thought the midlevel Internet deals were over," said Rafat Ali, editor of PaidContent.org, a site that follows the business of digital media, referring to acquisitions valued at several hundred million dollars. But the iVillage deal last week "means that some of the midsize properties are still in play."

Ali said that media companies would also like to acquire smaller companies - up-and-coming content sites that might cost tens of millions - but that there are few proven sites left to buy. A lot of smaller "good sites have gone," he said. Media companies "are looking at the new sites coming out of Silicon Valley" to determine what to buy next.

Media companies appear to be focusing their acquisition interest on sites that cater to niches but that have the potential for broad appeal. High on their shopping list are community networking Web sites like Myspace.com, which the News Corporation bought last year for $580 million.

Also of interest are sites that allow people to play casual interactive games; store, send, manipulate and print photos; build and store blogs; and research and shop for big ticket items, like cars. Also eliciting interest are "next generation" Web sites, like those focused on allowing people to search the universe of blogs more effectively.

The media companies' interest has to do with the continuing shift in the ways people consume entertainment and shop. Just as the advent of cable television carved up a once-concentrated block of network TV viewers, so has the Internet - with its literally millions of Web sites - created highly fragmented niche audiences.

For big companies, the key is to build or buy Web sites that attract those niche audiences, but in substantial numbers. For a Web site to at least pique interest of mass-market advertisers, it needs to have at least a million unique visitors a month; to be considered a major takeover candidate, it needs to have five million unique visitors, said Sharon Wienbar, a managing director with BA Venture Partners, a Silicon Valley venture firm that invests in Internet content companies.

In the case of iVillage, the company had 13.4 million unique visitors from the United States in February 2006, though that was down from 16.6 million in the same period a year ago, according to comScore Media Metrix, which measures Web traffic.

When the media companies guess right, the payoff has been growing, said Mark Pincus, chairman of Tribe.net, a social networking site. Mr. Pincus said the price that advertisers are paying to reach large, specific audiences has been increasing, and looks as if it will continue to do so.

Pincus noted that to reach a narrowly defined audience, the cost for having an advertisement seen 1,000 times, an advertising industry standard measure, is $20 to $50. An example, he said, would be visitors to a major portal's finance page.

He said that to reach broader audiences with specific interests - like the people who visit a job search site - ads command $4 to $10 per thousand impressions, a "huge jump" from $1 or $2 just two years ago.

To reach general audiences, like the masses who use Myspace.com on a regular basis, he said the price has jumped to $1 or $2 per thousand impressions, from pennies.

Pincus's site, Tribe.net, has been among the privately held social networking properties sometimes mentioned as acquisition candidates. Others in the category that are eliciting interest include xanga.com, a community of online diaries that had 7.2 million visitors in February, comScore said, as well as facebook.com and hi5.com. In December, 2005, Yahoo bought Del.icio.us, a company that makes software for bloggers and writers of online diaries, but did not disclose terms of the deal.

Perhaps the site most discussed and analyzed as a potential major takeover is Cnet, the operator of news.com, a site focusing on business and technology news. The price tag for Cnet, which is publicly traded, with a market value of almost $2 billion, would be $2.5 billion to $3 billion, said Mark May, an analyst for Needham & Co. who covers Internet services and digital media.

Cnet is "too expensive" to be a ready takeover candidate, May said.

Other analysts said Cnet had caused a lot of debate among major media companies, which were unable to determine whether how lucrative the Cnet audience could become.

And compared with valuing a public company like Cnet, putting a value on a privately held Internet company is even less of a science. While bigger companies are priced on a multiple of their revenue - based on comparable companies - smaller companies are based simply on what the market will bear, said Wienbar of BA Venture Partners.

May said public companies that might attract interest from major media companies included WebMD, a health information site with a market capitalization of nearly $2.2 billion; Bankrate.com, a financial news and information site whose stock is worth around $585 million; and Hollywood Media, a $157 million company that operates MovieTickets.com, a ticket-purchase site.

Industry analysts said another midsize company that had generated interest was PlanetOut.com, which has a market capitalization of about $170 million. The site caters to gay and lesbian interests. There is also TheKnot.com, a wedding site with a market value of more than $350 million.

Ali of paidcontent.org said another potential takeover candidate is Infospace, an Internet and mobile search company, whose stock is worth $750 million.

Media companies might also show interest in privately held casual gaming sites, like BigFishGames.com, iWin.com, atomshockwave.com and oberongames.com, Wienbar said. The sites are interesting to media companies, she said, because they "reach middle-aged women." all these are privately held. Ali said another group eliciting interest are companies that make games for mobile phones, including Mforma, Glu Mobile, and Digital Chocolate.