Inspired by http://www.stephenhobley.com/blog/2011/02/07/controlling-an-lcd-with-just-3-pins/
Steve Hobley in his blog has published a most excellent library for Arduino called LiquidCrystal595 that let you control an LCD display with only 3 pins .
To do this you need to connect the LCD to Arduino trough a shift register 74595, as a bonus you also get 2 pin free to drive a couple of leds for example.
What I'm going to show you is my hardware implementation, the schematic is pretty simple and universal.
Look at the site of Steve to get more explanation.
The finished product , I'm pretty happy with it , it's compact and easy to incorporate in projects