"Tracking Protection Lists offers consumers an opt-in mechanism to identify and block many forms of undesired tracking," she said via e-mail.

These , compiled by third-party organizations with expertise in this field, let users control which third-party site content can track them when they're online, and they can be designed to either "block" or "allow" certain third party content, she said.

"IE9 also includes the broadly discussed Do Not Track User Preference -- via both a DOM property and an HTTP header, as described in the W3C submission -- as a secondary method," she added.

Scott Meyer, founder and CEO of , said his company's products aim to create "transparency," not just opt-out mechanisms.

"Transparency enables consumers to make more informed decisions, and the fact is that the vast majority choose not to opt-out when presented with more information," he said in an e-mailed statement. "Our research ... shows that 67 percent of consumers feel more positive about brands which give them this level of transparency and control."