Kaplan and Haenlein (2010) identify seven types of social media:
collaborative projects (e.g., Wikipedia)
blogs and microblogs (e.g., Twitter, Kidblog.org)
social news networking sites (e.g., Digg and Leakernet)
content communities (e.g., YouTube and DailyMotion)
social networking sites (e.g., Facebook)
virtual game-worlds (e.g., Minecraft, World of Warcraft)
virtual social worlds (e.g., Second Life)