Which LCD?

The "standard" LCD is the one based on the Hitachi HD44780 interface. This is a parallel interface and you need at least 7 wires to communicate with the LCD. That's too many wires.

A new crop of LCDs are serial LCDs. Besides power, you only need two wires to communicate.

Several companies/individuals have developed low cost serial interface board for parallel LCDs. For example, you can buy serial LCD controllers from:

• Sparkfun
• Modern Devices
• Web4robot

My favorite is the 4x20 LCD from Web4robot because it supports I2C, it is priced right and there is a fine gentleman developing a library for this LCD (and also for other LCDs). As a bonus, this LCD also supports a 4x4 matrix keypad. See sidebar for links.