We've gotten cozy with the Web, clicking through sites as easily as we do TV channels with the remote control. Now, quit lollygagging and get to work! A new Web is emerging, and it depends on our sweat to succeed. Hundreds of new sites are trying to draw us out of our chairs and deeper into the cybersphere.

This is the new participatory Web: blogs, wikis, podcasts, social networks, forums. While connecting has always been central to the Internet, we were too distracted by those bargains on eBay, Amazon, and Expedia to notice. But in the past few years, behind-the-scenes upgrades have made it easier for ordinary people to take control of the Web, to broadcast their perspectives, whether that happens in a video clip of a guy demonstrating the "Evolution of Dance" or a downloadable recording of weekly Bible verses in Klingon. And all that expression is fast becoming more of a conversation. "The original [Web] browser was a one-way tool for reading, not writing," says Wendy Hall, a computer scientist at the University of Southampton in England. "In effect, we now can write on other people's websites."

Of course, this evolution of the Internet also is provoking a new gold rush, led by the sales of a few high-profile sites that have succeeded in sucking us in, including sensations like post-your-life's-story MySpace, which sold for $580 million, and the post-your-choppy-video YouTube, worth $1.65 billion. Think about it: We did the real work on those sites. Even Google qualifies among the new ilk, generating its immense wealth on the back of Web users-it measures the popularity of sites in ranking its search results.

It all translates into a whole new generation, to hear the evangelists talk. Wannabes already are trying to repeat the success of the dedicated social-networking sites like MySpace and Facebook. But equally telling is that every new website seems built on a plan that includes milking its users' efforts. For example, a company called Riya has developed software that can recognize faces in photos. Technologically, it's an impressive and useful advance. Still, Riya.com has made itself about networking users, who by working together can put more names to the faces in photos than they could working alone. Social networking alone won't guarantee a site's success, says Riya CEO Munjal Shah: "But you won't succeed without it."

Indeed, many sites already are feeling the effect of social networking on their bottom lines. Those that integrate socializing—such as Wikipedia.com, an encyclopedia built entirely by users—grow to the tune of millions of new visitors. Those that don't, like Encarta.com, stagnate, according to a recent report by the Pew Internet Project. The new approach merges two facts, says Susannah Fox, a coauthor of the report: "Everybody wants to be social, and everybody's online." Well, not everyone. But the trend is magnified when looking at young people. "They don't even think about "going online," Fox says. "Their lives are online."

A group of scientists, including Hall at Southampton, are trying to establish an academic field to study the Web's impact; they're surprised at the social links fostered by Internet technologies that researchers have unleashed. "How people use them changes what [the tools] are," she says. In other words, what we do online is spinning a whole new Web.

kidshealth.org

What would Dr. Spock have done with a DSL connection and a little knowledge of HTML? Probably made a website like KidsHealth, an online parenting encyclopedia with detailed advice on everything from what to eat during pregnancy to how to trim a baby's fingernails. Plus there are two bonus sections: one targeted at kids and another at teens. The teen site features dozens of articles on sexual health, drugs, and alcohol that could keep a young adult mesmerized for hours. Physicians and health experts review all the content before it's posted, and re-review it every one to three years.

PDRhealth.com

Drawing on the Physicians'Desk Reference, this site contains a full database of prescription information ranging from recommended dosage to side effects and what to do if you accidentally skip a pill. Those living with cancer or rare diseases can browse PDRhealth's listings of clinical trials, searchable by region and illness. And patients with cancer, lung, heart, and women's health ailments can get personalized advice about treatment options via the site's partner, NexCura. That service is meant to supplement, not substitute for, professional advice, explains Colleen Frary of NexCura.

WebMD.com

WebMD.com, the biggest of the medical websites, is growing (usnews.com/health, which offers similar features, was not considered for selection in this article). Many of its most helpful features are listed under "Health Care Services": a physician directory, an insurance guide, and an overview of Medicare benefits. Also useful are its subscription services, including an online weight-loss clinic ($4.99/week) and a health-record storage system for families ($29.95/year).

YourDiseaseRisk.com

"Looking for health information on the Internet is like looking for a diamond in a garbage dump," says Michael Springer of the American Academy of Family Physicians, quoting an old boss. At YourDiseaseRisk, more than a dozen Harvard-affiliated health professionals have done the dirty work for you. Their site sorts through research on disease risk to give users concise reports on how likely they are to develop five major diseases. The site's straightforward prose is helpful and encouraging. Unfortunately, without printing the page straight from your browser, there's no way to save the tips.