Two creative ideas. Perhaps an Ego Gallery will seem too strong a method to some. I wonder if anyone has tried importing something like this rating idea from posting sites.
BTW, it is not always a seemingly negative quality like Ego that can frustrate discussion. I was at one session where the person "sponsoring" the topic (if that is the name for the role of creating the topic, starting the session and remaining a the front of the room with a mic) niceky made the point that people were coming up with many diverse ideas and not deeping the existing ones. That's not always bad, but it can frustate some that want to come out a session with some fixed product, agreement or position.