In this workshop, we will explore the emergent methodological space of social media based HCI design and research. We will gather scholars and practitioners from different areas within HCI to discuss how social media platforms might support their practice. Through short presentations, open discussions, and design-led activities, we will examine the affordances of existing social media platforms and speculate future developments in this methodological space. The outcome of the workshop will be an interactive data visualization of existing social media platforms, their main characteristics, and their affordances for HCI design and research. Overall, we will begin to characterize the methodological space of social media based HCI design and research, setting the foundation for future developments in this space.