a smart meter based on raspberry pi, node.js, protovis and some electrical circuits. Results could look like this: https://github.com/ahoi-senn/smartMeter/blob/master/doc/Bildschirmfoto%202013-04-19%20um%2022.22.26.png. Results are here: http://ahojsenn.blogspot.com/2013/05/das-rapsberry-pi-smartmeter-lauft.html