MeWatt - Real-time energy monitoring and analysis of your appliances
Home-Assistant.io - Home Assistant is an open-source home automation platform running on Python 3.
Zuli Smartplug - Your invisible interface to the smart home
ioBroker - flexible and modular application for the IoT and Smarthome
Domus Smart Plug - Control your house with your iPhone (pre-launch)
openHAB - "empowering the smart home" - vendor and technology agnostic open source home automation