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/