Dave Winer, one of the "protobloggers" (I suspect he hates that term), provides an intriguing way to do a panel that isn't a panel.
The format is not far from the Socratic classroom, a discussion leader who pulls the interesting bits from the minds of the people in the room, with no sense of one person being a speaker and another being audience. Everyone is both a source and destination of thought.
The format solves the problems of the typical professional conference, the problem of droning self-important speakers who bore the audience and force the good stuff out into the hallway. The first goal of the format is to suck the good stuff back into the room. Everything about the format is designed to eliminate the boring, self-serving droning. But to do it respectfully. We're not running the Gong Show.
There's more in the piece; go give it a read.
It took me less than ten seconds to start wondering how an approach like this would work out for panels at a fan convention. Imagine one of those panels like "Shows You're Not Seeing And Should Be", stuff where 95% of what goes on is brought into the room by the audience.
Now, a strike in the Minus Column: it might be ill-suited to panels where people come specifically to hear someone speak at length from their own experience about a particular subject. Actually, even that sort of session could be retooled a bit: start with the lecture part of the whole thing, and then segue from that into something like the above, where his words are a springboard for further discussions in both directions. (Word of advice when giving a lecture like this: ask people to move to the front of the room. It makes things feel more like a conversation and less like a lecture. People at panels have this weird tendency to scatter all over the place, probably because they're still operating under the idea that other people are gonna get antsy about having their personal space invaded.)
I especially like the "No PowerPoints" rule. As a recovering PowerPoint abuser, I know full well how seductive those charts and bullet-lists can be for a presenter, and just how sleep-inducing they can be for everyone in front of them.