Raspberry Pi - 16x2 LCD
Should be fairly self-explanatory. Get a module and a Pi and wire them up.
Make sure that Pin 5 of the LCD is connected to GROUND otherwise you might send 5V back to your Pi, and you don't want to do that.
NB: At the moment, my module's contrast isn't right and I think I might need to add a potentiometer to control the contrast pin (pin 3).