I recently chaired Ark Group's KC UK Conference in London for the second year. I wanted to make it as interactive and engaging as possible and so I experimented with a new format.
Each speaker had 40 minutes to present. I e-mailed them all before the event to tell them that I wanted them to only speak for 20 minutes. That I would then give the audience 5 minutes to discuss their talk amongst themselves and then a full 15 minutes for Q&A. Most of the speakers kept close to time though one went to the full 40 minutes!
Quite simply, after each talk, I asked the audience to just turn to each other in twos or threes in their seats and have a conversation about the talk.
You can see the results in this little video clip I shot. Quite amazing, it worked every time and I had some good feedback - people enjoyed it.
I have used the technique at another conference since and it is going to become a standard part of my repertoire.