In this research, we investigate how different civil society organizations use network technologies and digital media to promote citizen participation around issues of public interest with a focus on social innovation and sustainability. Initially, we emphasize the urgency of the transition to more sustainable ways of living and argue the importance of citizen participation in this process. In this sense, we describe the global and emerging scenario of civic technologies observing the main strategies adopted by civil society organizations to promote citizen participation and highlight the power of initiatives of digital social innovation led by collaborative organizations, assembled around open technologies, open knowledge, open networks and open data. Next, we present a survey of several civic technologies initiatives implemented in Brazil during the first half of the 2010 decade. Based on the observed initiatives, we analyze the organizational and technological strategies of the new territories of citizen participation in Brazil and discuss some explorative digital media design practices that could contribute to processes of social innovation and citizen innovation. To conclude, we discuss the importance of open, collaborative and activist digital media design practices to help making sense around issues of public interest and to promote citizen participation towards more sustainable ways of living.