Housefish has a writeup on Kagen Schaefer's pipe-organ desk, which hides in its drawers a pipe organ that doubles as a fluidic computer, and which has stolen my heart:
At first glance, it’s a relatively ordinary desk, albeit very finely made out of exceptional wood, and with an unusual number of small drawers. Open a drawer though, and there’s a surprise- each drawer operates a wooden pipe organ tube on the back. Opening different drawers plays different notes and lets you play songs. If I stopped right there, a wooden pipe organ desk would already rank among the most novel and impressive pieces of wooden furniture either of us has seen.Kagen Schaefer Pipe Organ Desk | Housefish (via Crib Candy)
But there’s another secret. Inside the desk is a fluidic computer, operated entirely by the air pressure pulses created by opening and closing the drawers. This has been programmed so that playing a predetermined sequence of notes opens a secret compartment somewhere on the desk. It’s also reprogrammable, so you can set it to open when you play the theme to Star Wars, or whatever you want. And in case it wasn’t clear, this is made entirely of wood; there are no electronics of any kind. It is literally something that could have been built using technology available 500 years ago.