But although Spock and Zoominfo both stress the importance of being able to search by job title or other keywords, Michael Tanne, CEO of people-search engine Wink, says that isn't the most common need in people search. "That's not how 90 percent of searches are done," he says. "When you search for the iPhone, you want to see what's out there about the iPhone. But when you search for a person, you have a specific result in mind." While his site does allow users to search by tags, Tanne says that the tags are more commonly used to narrow down a search. Wink is able to search by variables such as location with more focus than the simple word recognition Google uses, Tanne says. For example, he notes, Wink would recognize that Framingham is close to Boston, and it would include both when a user enters "Boston" as a search term. (A spokesperson for Google says the search-engine giant currently has no plans to develop special features to improve people search.)

Singh says that Spock has indexed more than 100 million profiles so far--a reasonable start on the way to indexing every person in the world. But some people have raised privacy concerns. The people-search engines spider business sites and public Linked In profiles, but also social-networking sites such as MySpace. (Facebook information is kept private.) Business and personal information can appear on the same page, although Zoominfo attempts to index only the former. The sites' spokespeople all agree that the burden falls on the user to watch out for what's available online. "Whether you're managing it or not, you have a digital persona," Burdick says. Wink will remove profiles upon request, although not all people-search engines share that policy.

"The ability to see what you've put out there is an eye-opener to most people," Tanne says.

Credit: Spock

Crowd commentary: People-search engine Spock uses a combination of algorithms and user input to rank results and tag people with relevant keywords. The results can be quirky, as above: a search for "saxophonist" returns Bill Clinton as the top result, above jazz giants John Coltrane and Charlie Parker.