Two important trends in government that are emerging in the recent years have been on one hand the exploitation of the Web 2.0 social media, supporting a more extensive interaction and collaboration with citizens, and on the other hand the opening of government data to the citizens through the Internet, in order to be used for scientific, commercial and political purposes. However, there has been limited attempt of integrating them. Using a design science approach a second generation of open government data (OGD) platforms has been developed, which offer to the users both the ‘classical’ first generation functionalities, and also a comprehensive set of additional novel Web 2.0 features. The latter aim to provide support to the users in order to generate value from ODG. They enable users to become ‘prosumers’, both producing and consuming data. These novel capabilities for performing various types of processing, information and knowledge exchange, and collaboration were found to be useful and valuable by users in a first evaluation.