I am not married to Skype, it is just the application with which I have had the best and most experience, but part of that is because Google Talk is more limited. My main concern with letting anyone drop in is that the time I tried Ventrilo with some wotmaniacs before wotmanias demise people none of us knew kept showing up to be nosy and/or play annoying juvenile games like switching the conversation to a different channel so we all had to move to keep talking. On the other hand, without hosts there might be no risk of all the past drama over whether Chat Admins were abusing power or just doing their job.