I have often seen at conferences empty poster boards with small notes saying "Thank You Delta Airlines" or "Thank you United Airlines". Posters appear to be the most difficult thing to transport by plane! Before the conference I was at in Glasgow in July our posters went astray and then turned up looking like they'd been run over by the plane! This time our posters went astray and didn't reappear! So I have fulfilled a life-goal of having an empty poster board! Since all the posters from our department had gotten lost together they were reprinted so that we could still present our work. So no harm done!