For some reason the original post was deleted
I have been playing with Home Assistant (later HA) https://home-assistant.io
for a while and really had any good use of it. It was mainly controlling the lights and some other not so "smart" things.
Then I found a good use for it.
I have old HP printer on my home office desk that has OK button on top and it will print test page when pressed. Having 2 cats in the house I have wasted some paper and toner when they press the button while walking on the printer.
HA has Z-Wave capable power socket connected to printer.
Monitoring the status of the printer via IPP at HA I can switch on the socket when printer goes Idle -> Printing
It's on until the printer goes Printing -> Idle (there is 60s delay just in case the printing is still ongoing)
With this automation printer is switched off if there is no printing ongoing