Recently, online social networks have become one of the most relevant services on the Web. Although the reasons for this success can be manifold, this article underlines the re-articulation of social relationships that are allowed by the new practices of online self-exposure. Two main types of social media can be detected, friendship-driven and interest-oriented. However, one of the main implications of the rise of online social networks lies in the intertwining of those two different uses allowing, in a limited and controlled way, to mix strong and weak ties, conversation and content-sharing, contextual and strategic identity interplay.