Here's my suggestion: Contact your local science museums to request they add a distributed computing exhibit, which would consist of a computer running BOINC. The monitor showing a project screen saver would be an eye-catcher. Then, add some descriptive text about what the computer is doing, along with a QR code to download the android client to a smart phone.

The point of the exhibit isn't so much to crunch data itself, but to promote BOINC to visitors, who I assume would be inclined to participating themselves given they are visiting a science museum. Therefore, the computer probably ought to be low power so as not to drive up operating costs.

I'm guessing there are some folks on these board who have the creative skills to design such an exhibit, that could be easily built by some enterprising volunteers.