We have people participating in the Games MOOC who are doing tremendous work in pushing game based learning forward. Learning 2.0 is good group of people who have done other virtual online conferences. Their format is Blackboard Collaborate - but we can always get creative. Their Global Education Conference usually pulls in about 10,000 people total while their individual sessions can be 20 -30 people.
If you submit - please let us know, we will push it out on all the social media we have.
The discussions in the MOOC could make for some very interesting discussion panels!