Raspberry Pis really come with their own flavor of computer sickness, don't they.
I pulled one from the scrap pile at work and since then I've been thinking about what to do with it!
Many fun ideas, but the second I think about them in any way I realize that this can be done better and cheaper with either a microcontroller or a cheap (or often times free!) old computer.

@gigabecquerel Raspberry has one advantage compared to old PC - I have never seen old PC to automatically reboot and start to fully operational mode after power outage - Raspi did this many times without any problem... Second thing is a form factor and power consumption....

Plus, it was easy to connect custom hardware buttons / switches via GPIO.

But I agree in some cases much more simple MCU like Arduino can be better solution.