Social media are omnipresent today! But what is the role of social media in mathematics? This question is still wide open and in this talk I want to give a glimpse of the developments in this area. The focus will lie on mathematical blogs, but mathoverflow, the polymath project and the use of blogs in other sciences will also be addressed. Moreover, I will use the opportunity to present Mathblogging.org, an aggregator for mathematical blogs that can serve both as an index as well as a starting point for exploring the mathematical blogosphere.