Have to Ask What the App Costs? It's Not for You THE superrich have always had magazines, hotels and retailers catering to the special needs of their stratosphere. So it's no surprise that the digital world has caught up. Though luxury brands and services were initially reluctant to go online, a new corner of the Web and mobile app marketplaces has emerged, dedicated to making life easier for wealthy consumers. "They're playing off the affluent desire to be treated differently, expect a very high level of service and have something edited and vetted and pay for that," said Andrew M. Sacks, president of the Affluence Collaborative, a research firm studying affluent consumer behavior, and AgencySacks, a branding agency. Luxury advertisers then follow closely behind. "If you're successful in bringing several thousand affluent customers to a site, you're then prime to offer brands and advertising to that audience," Mr. Sacks added. Of course, wealthy people rely on the usual apps and sites - weather, news, sports and financial - according to the research firm Luxury Institute. Yet in other ways, the Web and mobile devices are ideally suited to well-off consumers. Much of today's wealth is being created by tech entrepreneurs who already live on their phones and computers, and by people outside the United States, so Web sites and apps are a more efficient way to reach them. And one of the latest trends in tech is particularly relevant to the affluent: services that straddle the digital and physical worlds, like apps that help people find an open seat on a private jet or a vintage Hermès handbag. Here are some of the most popular Web sites and apps among the wealthy, based on interviews with people knowledgeable about the luxury niche. All the sites are free to visit, though some require membership before all the details are unlocked. CONCIERGE SERVICE Close the Sydney Harbor Bridge for a marriage proposal? Deliver a metal detector to a vacation home in the French Alps to find missing keys, or send a circus troupe to a child's birthday party? These requests were each a click away for members of Quintessentially Lifestyle, a London-based service that provides round-the-clock concierge services for members" every whim. In case that's not enough, the Quintessentially Group provides several dozen other services, from fine art advising to bespoke educational consulting, wine buying, bodyguards and butlers. A mobile app is coming this month. TRANSPORTATION Uber is the app that made private Town Car service available to anyone with a cellphone. Passengers open the app and a car is on its way, seamlessly charged to the credit card number on file. Now that black cars are not just for the well-off, Uber is stepping it up. In certain cities like Paris and London, there is UberLux, with vehicles like S-Class Mercedes-Benzes. And last Fourth of July, Uber offered UberChopper, helicopters from New York to the Hamptons, summoned through the app for $3,000, including transportation to and from the helipads. One of Uber's founders helped start BlackJet, a similar service for private jets. Members can reserve seats on a private jet on the Web site or mobile app. Even with a $2,500 annual membership fee and cross-country prices around $3,500, it is less expensive than owning a private plane. TRAVEL Once wealthy travelers arrive at their destinations, they want tourist advice "filtered by people who are part of a similar cultural tribe," Mr. Sacks said. Jetsetter, the flash sale site for travel at all price points, includes a planning service that recently arranged a $65,000 vacation for a client, including shark diving in South Africa and beach lounging in the Maldives. Jetsetter offers rental homes, like two mansions on Calivigny Island, off Grenada. Rates start at $65,000 a night and include the private island, yachts and chefs. "The curation factor saves our busy members something as important as money, their valuable time," said Leigh Crandall, Jetsetter's managing editor. Inspirato, a private vacation club that has teamed with American Express, also rents private luxury residences. For a one-time fee of $17,500 and annual fee of $3,000, its 4,000 members choose homes from Aspen to Provence, complete with vacation advisers and on-site concierges. "These are the destinations and experiences that you might not be able to Google," said Amy Shannon, an Inspirato spokeswoman. Luxury hotels are also trying to save consumers time and headaches with mobile apps that let people order room service or arrange a wake-up call, massage or airport transportation before they arrive and without picking up the phone. One example is the Conrad Concierge app for Hilton's high-end line of resorts. SHOPPING Discerning collectors have been whispering about the site 1stdibs. Started in 2001 as a lead generation service for interior designers, this year it became a full-fledged e-commerce marketplace for antique furniture, fine art and vintage jewelry and couture. It has sold everything from a $3 million diamond mask owned by Elizabeth Taylor to a $400 first-edition Richard Avedon book. Traffic has doubled in the last year to one million unique visitors a month. "We are working in an industry that has been slow to convert to using the Internet to purchase luxury items," said Laura Schneider, a 1stdibs spokeswoman. What we have seen is that because of developments in technology and our reputation, we have been responsible for connecting the antiques industry to how consumers want to shop. Another site, Moda Operandi, sells designer clothes straight off the runway, before they are produced, like a $12,500 ivory silk evening dress from Calvin Klein's latest collection. ModeWalk also offers designer clothes, some of which were not previously available online, as well as personal stylists on the Web. They show clients items in private virtual showrooms and send selections by e-mail. Clients include a technology executive who relies on ModeWalk to choose her next three months of work, evening and weekend looks. SOCIAL NETWORKING Once upon a time, social networks for the rich, known as "Facebook for the few," were everywhere. Most, like one called Diamond Lounge, shut down. As Mr. Sacks put it, "Rich people don't just want to talk to rich people." But the most prominent, ASmallWorld, is still around, having recently reinvented itself after years of struggle. The invitation-only site shifted from selling ads to charging a $105 membership fee, and is redesigning its site and mobile apps. Its main offering is advice from like-minded people, mostly about travel but also about topics like jobs and real estate. With its location-based app, a member who just landed in Shanghai can find a recommended spot for a cocktail, for instance.