After finishing my first post on Google Power Meter, I thought that it would be better to provide a real project that demonstrates this concept. I found an interesting source which had all the necessary details to build your own project from scratch.
It consists of a small gadget that measures your power consumption and a Xigbee module that transmits data to your laptop. Also, there is a special software that can read data from the Xigbee module.
You can find the complete project here
Thanks to Limor for her great work!