I have a Sonos:Amp and connected to two in-ceiling speakers in my bathroom, which I wanted to control in an easy way. Attending a conference, I was presented to the Flic buttons and the idea came up, to use that as a simple way to control the Sonos unit in my bathroom. The unit itself is inaccessible, so I can't reach the buttons on the unit.
I've now archived this, using a Raspberry Pi and the linux-hci NodeJS library for Flic and a NodeJS library for Sonos.
One click activates play/pause on the Sonos unit, hold button, turns down the volume and double click, switches mode, so hold button now turns up the volume (after 5 sec. the mode switches back to turn down volume).