At the inaugural open house, Shawn and I installed some 30/m pitch NeoPixels to the frame around the front window. They aren't super visible from the outside because of the window sashes.
The plan, as it stands is to re-attach the NeoPixels to the actual window panes (non-permanently?), and connect the strip to an Arduino Mega TinkerKit (http://www.robotshop.com/en/arduino-adk-kit.html) that we happen to have lying around…
We'll find some way to attach the appropriate software/drivers/libraries to the project so that a visitor to the space can control the NeoPixels as quickly and as easily as possible. This might take the form of a USB stick, or maybe a preloaded Raspi with appropriate accoutrements. Plus a cool info panel letting people know that deep interaction is invited…
I think that the TinkerKit sensors have a fairly consistent mounting hole spacing, so it might be cool to make a LEGO style control panel so that the sensors stay in place firmly but not permanently.
In fact, the whole project should have the feel of an open LEGO bin at the Discovery Centre. Build what you want, but know that the next person is invited to disassemble and reassemble to taste.
Once this project is up and running, we could create a monthly challenge for participants. (Maybe successful participants get a laser-cut wooden nickel identifying the challenge they completed):