While the collection and monetization of user data has become a main source for funding “free” services like search engines, online social networks, news sites and blogs, neither privacy-enhancing technologies nor their regulations have kept up with user needs and privacy preferences. The aim of this chapter is to raise awareness of the actual state of the art of online privacy, especially in the international research community and in ongoing efforts to improve the respective legal frameworks, and to provide concrete recommendations to industry, regulators, and research agencies for improving online privacy. In particular we examine how the basic principle of informational self-determination, as promoted by European legal doctrines, could be applied to infrastructures like the internet, Web 2.0 and mobile telecommunication networks.