Most of the things I've made so far have interfaced to a 2 line LCD display based on the LiquidTWI2 library. Every time I've wound up making a small board with a 4 pin i2c connector to go off to the OpenEVSE LCD backpack.
It's just occurred to me...
Why not put the controller on the backpack? In fact, why not make the ATTiny equivalent of a combination of the Uno and the AdaFruit RGB shield, more or less?
I'm envisioning something the size of the LCD backpack that would have a power jack on it, an ATMega328 TQFP, an MCP23017 wired up to an LCD, all wired up to a pin header designed to connect up to a breadboard for adding whatever it is you want to prototype.
But what to call it? I'll have to think on that one.