Agents of Choice: Tools that Facilitate Notice and Choice about Web Site   Data Practices
  A variety of tools have been introduced recently that are designed to help people protect their privacy on the Internet. These tools perform many different functions in-cluding encrypting and/or anonymizing communications, preventing the use of persistent identifiers such as cookies, automatically fetching and analyzing web site privacy policies, and displaying privacy-related information to users. This paper discusses the set of privacy tools that aim specifically at facilitating notice and choice about Web site data practices. While these tools may also have components that perform other functions such as encryption, or they may be able to work in conjunction with other privacy tools, the primary pur-pose of these tools is to help make users aware of web site privacy practices and to make it easier for users to make informed choices about when to provide data to web sites. Examples of such tools include the Platform for Privacy Preferences (P3P) and various infomediary services. 
Lorrie Faith Cranor