Recent efforts to increase online privacy by offering the user a more general choice to opt out of online tracking were mainly pushed by the FTC in late 2010. As the FTC explicitly omitted technical details, browser developers started to implement what they thought might be appropriate to either limit user tracking directly, or let the advertiser know about the user’s wish to not be tracked. This paper gives a short overview on the positions and arguments of stakeholders and evaluates the technical proposals and implementations aiming to support the consumer in keeping control over his personal data.