Vinod blogged about a 16×2 LCD with data over power line:
Then I just thought why even 1 wire for data? Because we can easily multiplex the 1 wire data line with the Vcc line by keeping a diode + capacitor combination towards the LCD power supply pin. I am using an arduino board to do the serial to parallel conversion + some packet parsing and lcd backlight brightness control. I am not a huge fan of Arduino but for this simple proof of concept, I don’t want to bring out a Makefile folder with muliple files. I picked the Arduino UART RX as the serial receiver. RX pin is connected directly to the input Vcc, but before the schottky diode.
See the full post in his blog.
Check out the video after the break.