@mike Has a pretty cool use for this, I gather 
Personally, I use energy monitoring to see what devices are being used and create events based off of that --- our treadmill, kitchen appliances (I get a notification if pizza is done being made, or if someone made popcorn --- different gadgets that use power in certain ranges that are easy to detect). That's part of making all of this fun: "Hey, enjoy the pizza!", or not letting me turn off the lights in the morning if I don't work out on the treadmill.
I have an energy meter that tracks a Philips wakeup alarm for our roommate. When her alarm goes off, the lights in her room fade up as the light on her alarm fades up.
I use energy meters to detect when laundry is being done, as well.
I've yet to set up home-energy monitoring. I intend to use it to get a good idea of when our power is being consumed, though, and create an energy plan around that.
