Online services have been tracking consumer behavior for a decade without creating problems for consumers, said Paul Rubin, a fellow at the Technology Policy Institute (TPI), a free-market think tank, and an economics and law professor at Emory University.

"Everyone talks about how consumers don't know what's going on, and if they knew what's going on, they'd be horrified," Rubin said. "The reason they don't know about it is they haven't bothered to learn about it, and the reason they haven't bothered to learn about it is because nothing bad has happened."

There's little evidence of data collected by online ad networks being used for identity theft, Rubin said. Instead, consumers see multiple benefits from giving up some personal data, such as information about what sites they visit, he added.

Several lawmakers have said privacy legislation is likely to be introduced later this year, but too many regulations could mean that now-free services like search, maps and Web mail could start to cost money or no longer be available, said Rubin, co-author of a on privacy and online services.

“More privacy, however, would mean less information, less valuable advertising, and thus fewer resources available for producing new low-priced services," the TPI paper argues. "It is this trade-off that Congress needs to take into account as it considers new privacy legislation.”