Introduction: Shift Me Kit: 595 and 165 Shift Register Kit
Can you imagine having to hook up all of the lines necessary just to get 74HC595s to shift a bajillion bits for you? Yeah. Neither could we. So we made breadboard-friendly shift register modules that are capable of being hooked up ad infinitum to each other. Each board has 8 LED indicator lights and 8 switches that allow you (and your microcontroller or computer) to read or write any of the LEDs/switches through only six wires.
This is essentially awesome for user input and output. It could be used for binary input/output, step sequencers, and recording/reading what options are turned on or off. And since they can be connected to each other, if you connect two boards together, you can clock 16 bits in instead of just 8, and so on.
You can find it here: https://www.tindie.com/stores/tymkrs/
And more information here: http://www.tymkrs.com/kits/595-shift-register-module/