Here is an older paper (1998): http://web.njit.edu/~turoff/Papers/CDSCMC/CDSCMC.htm “Collaborative Discourse Structures in Computer Mediated Group Communications” I envision a system where a moderator could change the structure of the response area in ways to bring in those who were in read-only or -mostly mode and engage them in the conversation. Instead of the typical text entry box, their might be a short questionnaire or something else to encourage participation. The system might even be set up so that a response would be required to move forward. Lots of interesting possibilities.