2d presentation: Some people noticed in the playsh presentation that the slides transitioned to each other in an unusual way. They didn't just slide forward to the next one, but would slide left if we stepped back, and we occasionally stepped up and down by accident and moved around.
As it happens, the presentation slides were arranged on a 2d grid to allow us to move around them in any direction we chose. The presentation itself was given in custom-written slideshow software written for my company, and controlled by a hand-help accelerometer connected to my laptop. Tilting the accelerometer board left moved left across the presentation, tilting up moved up, and so on.
There wasn't any particular reason to do this, only that the geographic layout of the slides reflected the geographic notions in the playsh code, and that it seemed like a good idea last Thursday, when I thought of it.