The use of personal data has incredible potential to benefit both society and individuals through increased understanding of behaviour, communication and support for emerging forms of socialisation and connectedness. However, there are risks associated with disclosing personal information, and present systems show a systematic asymmetry between the subjects of the data and those who control and manage the way that data is propagated and used. This leads to a tension between a desire to engage with online society and enjoy its benefits on one hand, and a distrust of those with whom the data is shared on the other. In this chapter, we explore a set of obfuscation techniques which may help to redress the balance of power when sharing personal data, and return agency and choice to users of online services.