Online tracking has become big business. The FTC is proposing a way to control it that would be analogous to the Do Not Call registry.
http://news.yahoo.com/s/ap/20101201/...c_do_not_track
"WASHINGTON – Federal regulators are proposing to create a "Do Not Track" tool for the Internet so that consumers could prevent marketers from tracking their Web browsing habits and other behavior in order to target advertising.
"The proposal, inspired by the government's existing "Do Not Call" registry for telemarketers, is among the recommendations outlined in a privacy report released Wednesday by the Federal Trade Commission. The report lays out a broad framework for protecting consumer privacy both online and offline as personal data collection becomes ubiquitous — often without consumer knowledge.
Another good link is:
http://ftc.gov/opa/2010/12/privacyreport.shtm