The Open Energy Monitor Project is a good one that I can see the Spark Core being used in.
There are many features that @phec is not using that the Open Energy Monitor Project is capibable of that are pretty cool.
There is a wireless display that shows the system and weather status. http://openenergymonitor.org/emon/emonglcd
And then they have a killer online interface that you can customize as you like. The spark core can be used to get this data from your system to the internet for logging and graphing.
I personally would like to explore using the Spark Core to push data to this free online interface: http://emoncms.org/site/home
Here is an example of their customize able online interface. http://www.emoncms.org/jb79/Solar1
Just wanted to expand on what is possible with the Open Energy Monitor Project. I’m looking forward to seeing the Spark Core being used in this open source system.
@phec thanks for being the first to share this and how your using the Spark Core instead of the Arduino equipment.