I have recently thought of using raspberry pi 2 for digital signage. It has the interface and chassis layout for it. It is small and it can be customize for any signage needs.
I recently wrote a program that write itself and learn and write own code(kind of). The best application that may need it is robotics and data critical systems that needs to adapt quickly to different situation. It also perfect for games that has ai that level up by self and learn from player and reprogram itself.