Usually I do constant research on projects to automatize things at home, like energy monitor. Long time ago I came across this little nice post, explaining in a very simple way how to monitor your home energy consumption. On top of that he is using an ethernet shield that outputs the information through a MQTT feed to xively.com where it is processed and transformed in a nice bar graph.
UPDATE: Xively is not free anymore so this example will not work. Soon I will post an alternative using other types of logging.
UPDATE2: Here you can check another project using sparkfun server and thingspeak server
Here is the link to the post: http://jonarcher.info/2014/03/arduino-based-electricity-monitor/
Hackaday post as well: http://hackaday.com/2014/08/01/electricity-monitoring-with-a-light-to-voltage-sensor-mqtt-and-some-duct-tape/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+hackaday%2FLgoM+%28Hack+a+Day%29
Xyvely feed (not working at the moment): http://xively.com/feeds/73975854
My intention is install it in my home so I can energy monitor the house. Having a live energy graph will help me understand how we are consuming electricity and hopefully save some money in the next energy bill.
Hope you also find it so interesting as I do.