Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
Gladys - An open-source home assistant powered by a Raspberry Pi 🗣️
SmartRent - Smart home automation for property managers and renters
Hue Brain Games - Play interactive games with your Philips Hue lights
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation
Domus Smart Plug - Control your house with your iPhone (pre-launch)