Reading through articles that analyze online conversations I found that next to well known social network analysis there are also several other ways to visualize and through visualisation analyse online conversations.Turner, Smith, Fisher and Welsher (2005) is a good example article where they use several different methods to visualize Usenet conversations (in time period from 2000 to 2004).
First is a method called Treemaps developed by Shneiderman.
Basically (if I understood it correctly) it transposes large trees into a smaller visualization - a box containing large numbers of boxes. Turner et al. (2005) used this method to depict hierarchies in Usenet according to two variables (thus two different sets of boxes):
-number of posts within a hierarchy (and within it newsgroups, threads),
-number of replies within a hierarchy
Similarly this method could be applied to visualization of conversations on globalism or similar issues on YouTube (the only problem is, that I have no idea how to employ it).
An interesting employment of Treemaps is Veskamp's Newsmap where he creates a program that instantly visualizes current Google news according to type of news (e.g world, national, sports etc.) and for 11 different nations.