I like the ideas of an RB67 back project and the HIE project, too. A project that includes a camera like the Nettar is smart because it folds up so nicely for shipping.
A Polaroid project, as suggested by bdial, sounds good, too. We could include an extra film pack or two with the camera so that 20 or 30 people could participate. Actually, this camera could travel until there's no film available while every tenth person could mail in a completed pack of ten prints and this way we could see results while the Polaroid travels the world. Kinda like Voyager I and II traveling around the solar system and sending in pics as it goes along. People can sign up as the project continues on and on. We could use a cheapie Polaroid or a nicer one for durability as the miles could really pile up.
Other than that, I'm willing to shoot with whatever camera shows up at my doorstep. :-)