I recently saw this little board, which provides a little screen (120×120 1.4″) and some buttons, in a nice little form-factor which would stack directly onto a Pi Zero. I figured this would allow a neat setup which would allow testing of various setups and also something I could use as a user interface for many other Raspberry Pi based projects.
I decided this would make a very nice little RetroPi setup, see how I got on in my Guide to…Mini RetroPi setup.
Meltwater's Raspberry Pi Hardware 