I have a pi3, pi2, and a burnt out pi1. Used the pi2 for xbmc media player sometimes. Have the cameras for them, played alot with motion capture, opencv, and speech recognition, but enjoyed the pi most as a headless server that scraped news and weather from the internet. It would collect and chart data from the microcontrollers, and act as the main interface for their data and control. Retro pi would be fun too, i never got around to trying it out, but i did get the ps/2 controller hooked up to the pi.