You can usually look up your electric usage history by logging into your utility company's online account.
Other than that, when it comes to electricity, the added value from a site like Fully is kind of lost in my opinion as it would be like comparing apples to oranges... no two households are the same. At least with cars, you can compare usage from the same make/model.
Or did you mean like a forum where users would post tips about how to cut down on your electricity usage?
If I'm reading their announcement correctly, they'll automatically calculate and track your electric costs for you, based off your bank's utilities bills. Or something? Maybe Marc can add some details?
They haven't launched the actual service yet, but hopefully it'll enable better awareness of energy use and conservation.