That's according to Truste, a nonprofit privacy organization that released a new study Friday examining consumer attitudes toward behavioral targeting and privacy--topics that are increasingly drawing the attention of lawmakers and the media.

Nearly three out of four people, or 71%, said they realize that companies track their Web browsing activity for purposes of sending them targeted ads. The majority--57%--said they are not comfortable with the practice, even when their browsing history can't be linked to their names.

At the same time, 72% of Web users also told researchers they find irrelevant ads "intrusive and annoying," although one key strategy for displaying relevant ads relies on behavioral targeting, or monitoring where people go online and then determining their interests. "The study has unearthed some basic contradictions," said Dave Morgan, founder of behavioral targeting company Tacoda and a former ad executive at AOL. "The vast majority of consumers do not like irrelevant ads."

But at least some Web users indicated they would welcome targeting that doesn't rely on monitoring their Web activity. Fifty-five percent said they would take an anonymous survey in order to limit ads to the products, services or brands they use, while 37% said they would be willing to provide personal contact information with a survey.

Morgan said he doubted surveys would be effective. "Most consumers really don't want to trouble with that," he said. "They want things to just work."

But with many users so skittish, online ad companies might find it difficult to gain people's trust.

"There's fear, uncertainty and doubt," said Carolyn Hodge, Truste's vice president of marketing. "The key is really convincing these people that the industry is going to be responsible with the information," she said, adding that some well-publicized privacy glitches seemed have left people uneasy.

Among the most notorious online privacy debacles was Facebook's introduction of the Beacon program, which told people about their friends' purchases, and its 2006 news feed program, which notified members about changes to their friends' profiles.

Tracking performed by Tacoda and many other behavioral targeting companies is anonymous--pegged to cookies that are placed on people's computers, but not tied to name, e-mail address or other information that could be used to identify individuals.

Many networks that track people online give consumers a way to opt-out of tracking, as does the Network Advertising Initiative--an umbrella group that includes some of the biggest online ad companies like AOL's Advertising.com, Microsoft's Atlas and Yahoo--but only a small proportion of users opt-out through those mechanisms. Morgan estimated that less than 10% of the users who click on Tacoda's privacy policy opt-out.

A large percentage, however, have found another way to opt-out: they delete their cookies. Fifty-four percent of Web users said they erase cookies two to three times a month, according to Truste.

The report also found some support for a do-not-track registry, proposed to the government last year by a coalition of groups including the World Privacy Forum and Center for Democracy & Technology. Forty-two percent of Web users said they would join such a registry, according to Truste.

Truste's report was based on a February survey of 1015 Web users conducted by TNS Global. The study comes as state lawmakers in New York and Connecticut are mulling legislation that would regulate online tracking, and as the Federal Trade Commission is considering new behavioral targeting guidelines.

That agency highlighted behavioral targeting and privacy as key concerns in a new report, "Protecting Consumers in the Next Tech-ade," released on Friday.

"Perhaps the greatest single challenge associated with consumers' expectations for control is ensuring that the underlying data used to facilitate targeted marketing is collected, maintained, and used in a manner that is transparent and consistent with the law," the FTC wrote.

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