Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
SOUNDS - Discover music with friends
ioBroker - flexible and modular application for the IoT and Smarthome
Spotify - Map shows when two people play same song at same time
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation
Songlink - Share music with anyone.