I'm actually working on a project called the Anywhere Organ. The idea is to create a mobile, modular pipe organ that can stealthily be set up in any building/park/alley/office foyer turning the space into a giant musical instrument.
I'm buying up old organ pipes off of ebay and was planning on using an arduino multiplexed to deliver outputs to the solenoid valves that deliver air to the pipes. Having access to 60 I/O pins would be incredible.