Running a 3d printer alone at home is not necessarily the best idea - so I was looking for a way to force it off from remote. As OctoPrint user I stumbled upon a plugin to control TP-Link Smartplugs, so I decided to give them a try. What I found especially nice on the HS110 model was that it is possible to monitor power usage, current and voltage. Of course I wanted to have a long term graph of it. The result is a small collectd plugin, written in Python. It is available on github: https://github.com/bzed/collectd-tplink_hs110.
Enjoy!