Bear in mind that this was a daydreaming scenario… it's ludicrous:
I was thinking that, assuming that there's leakage to the ground of house, it would be possible to use that power for something… give or take. It actually came out of the silliness of "free power" generators. In the craziness of my daydream, I was thinking it could be used to charge a battery or two. The problem is that grounds are used for safety reasons, which means that there would have to be some way to handle surges in current. The solution that my mind came up with was to have a bypass on the charging circuit that was activated if the power exceeded a limit (like a circuit breaker).
Now I'm not going to try that insanity. But I do want to know if there's such a device out there (and I can't imagine that there isn't).