Tim and Nina Zagat, the royal couple of the restaurant review business, are holding court at Jean Georges, where the sunlit dining room offers a view of Central Park West. They are attended to as if they were visiting heads of state. Yet when they leave, the Zagats can greet each member of the kitchen staff by name.

Tim, 67, and Nina, 65, take advantage of all the perks of running a global review business—the instant access and upgrades—but always make sure to pay the bill. And when they're out on the town, they stress to chefs and managers alike that they're not the ones writing the reviews. Whether they're penning co-bylined articles for the New York Times on why it's hard to find good Chinese food or ringing the opening bell at Nasdaq, the two are inseparable. Even their navy suits look as if they've been coordinated.

But there are rumblings of trouble for the couple's empire. So with online search giants and food sites like Yelp and Chow, which is owned by CNET and run out of San Francisco by former Industry Standard editor Jane Goodman, encroaching on their realm, the Zagats are striking back. They now offer a redesigned version of their website for cell phones, so that on-the-go diners can get a review quickly. And in the process, they are reaping rewards from the rapidly growing amount of advertising headed toward the mobile sector.

Making Zagat available across every conceivable platform has been one of Nina's main responsibilities inside the company, while Tim focuses more on sales and marketing.

In October, Zagat's website will go through another round of tweaks as part of an overall effort to ramp up the free, ad-supported content online: For instance, the site will offer video and entertainment-oriented content that will be updated more frequently. And as with Yelp, visitors to Zagat's site are encouraged to publish their own reviews online.

Like many companies, Zagat has struggled with its online strategy, first offering everything for free when it launched in mid-1999 and later making users pay for much of the content as the service grew.

The site now offers a mix of premium and free content. A $25 subscription gives customers access to the company's 30,000 official reviews and scores. The company won't say how many online subscribers it has or how its revenue pie is divided, though one executive describes subscriptions as the heart of the business. Advertisers appearing on the site include Audi, BMW, Mercedes, Continental, Delta, Charles Schwab, HSBC, and Visa Signature.

The company has a long way to go to catch its online competitors. Zagat.com was ranked the 62nd-most-visited food-and-beverage reference site for July, while Chow's Chowhound came in at No. 18 and Food Network topped the list, according to Web measurement firm Hitwise. According to Nielsen/Net Ratings, another online measurement service, Citysearch reached 11.7 million unique visitors during July, while Zagat.com reached 665,000. (Epicurious.com, it should be noted, is a food-and-beverage sister site to Portfolio.com.)