GPO Breakout Board
This board breaks out the 74HC595 bit shifter IC. It can be daisy chained and each chip will provide 8 output pins over SPI.
I designed this board to show multiplexing and daisy chaining capabilities for the 74HC595 chip. The design could look a bit odd since the resistors and LEDs are positioned in a strange way.
This is done so the LEDs are optional. Instead of the resistors you could also solder regular pin headers at the top, to gain 8 output pins instead of LEDs.