From a nokia 1100 damaged, but with functional LCD, It used a PIC18F2520 to process text and variables display, as the temperature. Since the communication with the LCD is slow and series, It used the internal 8 MHz crystal to command the screen by PIC.
The screen seems transparent and has a low consumption (10mA), same with brightness. With this, You can reuse functional screens of mobile phones that were cancelled.
The main routines are in this site, having been changed to the PIC above.