Myke Predko has a post online (somewhere) using a 74LS174 and a 2-wire interface (literally Data and Clk) to drive the 'shift register' and the LCD -- nothing else than a diode, resistor, and supply rails.
I've used this a few times - (just finished a new project this morning with a 20x4 LCD)
If you use a resistor ladder for pushbuttons - the whole front panel occupies 3 pins, and almost no parts!