With countless data points at their fingers, internet advertisers are poised to deliver the most relevant ads in history. But before that happens, the Federal Trade Commission will weigh in on user privacy with two days of hearings. Among the items being bandied about in Washington is the possibility of a mandatory do-not-track list that would prohibit advertisers from using behavioral targeting on users who opt to maintain maximum anonymity.

The proposed mandatory do-not-track list is the brainchild of a coalition of consumer advocacy groups. The idea comes on the heels of AOL's announcement that it would voluntarily offer users the chance to opt out of tracking.

While data tracking is anonymous, privacy advocates fear that marketing firms will soon be able to determine the identities of internet users.

"It's a digital data vacuum cleaner on steroids, that's what the online ad industry has created," Jeff Chester, executive director of the Center for Digital Democracy, told The New York Times. "They're tracking where your mouse is on the page, what you put in your shopping cart, what you don't buy. A very sophisticated commercial surveillance system has been put in place."

Advertisers insist that better targeting leads more relevant ads, which in turn keep the internet stocked with free content.

The FTC says it sees both sides of the issue. Eileen Harrington, deputy director of the FTC's Bureau of Consumer Protection, said targeting does offer a valuable service to users, but pointed out that some consumers may not be willing to pay the price.