The Nielsen Company, a global research, ratings and data firm for all types of media, has published a new report outlining the impact of social media titled "State of the Media: The Social Media Report Q32011". It identifies current trends in social media usage and influence.
http://blog.nielsen.com/nielsenwire/social
Wikipedia, the free encylopedia, offers a segment titled "Shaping" which outlines social media classifications (July 2011).
Social media take on many different forms, including Internet forums, weblogs, social blogs, microblogging, wikis, podcasts, photographs or pictures, video, rating and social bookmarking. By applying a set of theories in the field of media research (social presence, media richness) and social processes (self-presentation, self-disclosure) Kaplan and Haenlein created a classification scheme for different social media types in their Business Horizons article published in 2010. According to Kaplan and Haenlein there are six different types of social media: collaborative projects (e.g. Wikipedia), blogs and microblogs (e.g. Twitter), content communities (e.g. Youtube), social networking sites (e.g. Facebook), virtual game worlds (e.g. World of Warcraft), and virtual social worlds (e.g. Second Life). Technologies include: blogs, picture-sharing, vlogs, wall-postings, email, instant messaging, music-sharing, crowdsourcing, and voice over IP, to name a few. Many of these social media services can be integrated via social network aggregation platforms.
Orgnet.com provides an illustrative narrative explaining the concept of the node of a social network.
http://www.orgnet.com/sna.html