What about supporting a conference call with several people listening in? This comes in handy with business meetings when the project leader or CEO is discussing plans for the company or the project. Usually only one person will be talking at a time but each attendee can raise their hand by pressing a button so the moderator can then allow them to talk. The moderator can also mute people or have a timer on how long they can talk and this timer counts down. For example a 5 minute timer has a progress bar at the top of the app and it scrolls to zero. This prevents attendees from monopolizing the conversation. You could also have a side chat window for listeners to text the moderator questions you'd like answered. Something like Goto Webinar but without the video. Add video later if enough people want it.