I love this video of Gever Tulley talking about something called 'Tinkering School'. It is not a new TED Talk, but it is a great one.
My favourite quote is: "Robyn and I acting as collaborators keep the landscape of the projects tilted towards completion." This is a great perspective on the role of the facilitator - not to get to a particular predetermined outcome, but to keep the participants headed in roughly a positive and useful direction.
Another quote that tickles my fancy is, "decoration of the unfinished projects is a kind of conceptual incubation". Purposeful doodling, or maybe doodling with beneficial side-effects?