In practice, however, self-governing communities like Wikipedia — or algorithmically self-correcting systems like Google — often leave people feeling misrepresented and burned. Those who think that their online reputations have been unfairly tarnished by an isolated incident or two now have a practical option: consulting a firm like ReputationDefender, which promises to clean up your online image. ReputationDefender was founded by Michael Fertik, a Harvard Law School graduate who was troubled by the idea of young people being forever tainted online by their youthful indiscretions. “I was seeing articles about the ‘Lord of the Flies’ behavior that all of us engage in at that age,” he told me, “and it felt un-American that when the conduct was online, it could have permanent effects on the speaker and the victim. The right to new beginnings and the right to self-definition have always been among the most beautiful American ideals.”

ReputationDefender, which has customers in more than 100 countries, is the most successful of the handful of reputation-related start-ups that have been growing rapidly after the privacy concerns raised by Facebook and Google. (ReputationDefender recently raised $15 million in new venture capital.) For a fee, the company will monitor your online reputation, contacting Web sites individually and asking them to take down offending items. In addition, with the help of the kind of search-optimization technology that businesses use to raise their Google profiles, ReputationDefender can bombard the Web with positive or neutral information about its customers, either creating new Web pages or by multiplying links to existing ones to ensure they show up at the top of any Google search. (Services begin from $10 a month to $1,000 a year; for challenging cases, the price can rise into the tens of thousands.) By automatically raising the Google ranks of the positive links, ReputationDefender pushes the negative links to the back pages of a Google search, where they’re harder to find. “We’re hearing stories of employers increasingly asking candidates to open up Facebook pages in front of them during job interviews,” Fertik told me. “Our customers include parents whose kids have talked about them on the Internet — ‘Mom didn’t get the raise’; ‘Dad got fired’; ‘Mom and Dad are fighting a lot, and I’m worried they’ll get a divorce.’ ”

Companies like ReputationDefender offer a promising short-term solution for those who can afford it; but tweaking your Google profile may not be enough for reputation management in the near future, as Web 2.0 swiftly gives way to Web. 3.0 — a world in which user-generated content is combined with a new layer of data aggregation and analysis and live video. For example, the Facebook application Photo Finder, by Face.com, uses facial-recognition and social-connections software to allow you to locate any photo of yourself or a friend on Facebook, regardless of whether the photo was “tagged” — that is, the individual in the photo was identified by name. At the moment, Photo Finder allows you to identify only people on your contact list, but as facial-recognition technology becomes more widespread and sophisticated, it will almost certainly challenge our expectation of anonymity in public. People will be able to snap a cellphone picture (or video) of a stranger, plug the images into Google and pull up all tagged and untagged photos of that person that exist on the Web.

In the nearer future, Internet searches for images are likely to be combined with social-network aggregator search engines, like today’s Spokeo and Pipl, which combine data from online sources — including political contributions, blog posts, YouTube videos, Web comments, real estate listings and photo albums. Increasingly these aggregator sites will rank people’s public and private reputations, like the new Web site Unvarnished, a reputation marketplace where people can write anonymous reviews about anyone. In the Web 3.0 world, Fertik predicts, people will be rated, assessed and scored based not on their creditworthiness but on their trustworthiness as good parents, good dates, good employees, good baby sitters or good insurance risks.

Anticipating these challenges, some legal scholars have begun imagining new laws that could allow people to correct, or escape from, the reputation scores that may govern our personal and professional interactions in the future. Jonathan Zittrain, who teaches cyberlaw at Harvard Law School, supports an idea he calls “reputation bankruptcy,” which would give people a chance to wipe their reputation slates clean and start over. To illustrate the problem, Zittrain showed me an iPhone app called Date Check, by Intelius, that offers a “sleaze detector” to let you investigate people you’re thinking about dating — it reports their criminal histories, address histories and summaries of their social-networking profiles. Services like Date Check, Zittrain said, could soon become even more sophisticated, rating a person’s social desirability based on minute social measurements — like how often he or she was approached or avoided by others at parties (a ranking that would be easy to calibrate under existing technology using cellphones and Bluetooth). Zittrain also speculated that, over time, more and more reputation queries will be processed by a handful of de facto reputation brokers — like the existing consumer-reporting agencies Experian and Equifax, for example — which will provide ratings for people based on their sociability, trustworthiness and employability.

To allow people to escape from negative scores generated by these services, Zittrain says that people should be allowed to declare “reputation bankruptcy” every 10 years or so, wiping out certain categories of ratings or sensitive information. His model is the Fair Credit Reporting Act, which requires consumer-reporting agencies to provide you with one free credit report a year — so you can dispute negative or inaccurate information — and prohibits the agencies from retaining negative information about bankruptcies, late payments or tax liens for more than 10 years. “Like personal financial bankruptcy, or the way in which a state often seals a juvenile criminal record and gives a child a ‘fresh start’ as an adult,” Zittrain writes in his book “The Future of the Internet and How to Stop It,” “we ought to consider how to implement the idea of a second or third chance into our digital spaces.”

Another proposal, offered by Paul Ohm, a law professor at the University of Colorado, would make it illegal for employers to fire or refuse to hire anyone on the basis of legal off-duty conduct revealed in Facebook postings or Google profiles. “Is it really fair for employers to know what you’ve put in your Facebook status updates?” Ohm asks. “We could say that Facebook status updates have taken the place of water-cooler chat, which employers were never supposed to overhear, and we could pass a prohibition on the sorts of information employers can and can’t consider when they hire someone.”