Unconferences (see BarCamp as an example) run on a model of maximum audience participation, where the participants are also the presenters. This means that we strongly encourage everyone who attends to give either a 30 minute session, a 5 minute lightning talk, participation in a panel or round table discussion, or contribute in some other meaningful way. The actual schedule of which sessions go where is decided within the first 30 minutes of the camp, shortly before introductions and kickoff.
It works.