I would love to see a small, pass-through plug-in device with energy monitoring that has no integrated relay. Plug the device into the outlet, plug the load into the device. It would need to be able to support a decent wattage, but the most important feature (to me) is a complete inability to affect the load. In other words, the load could never be turned off by the device (by accident, through a hack, power loss, by device reset/failure, etc.). IMO, would only need to support the standard energy reporting command class.
- Detect energy level in excess of threshold for notification of load running (sump pumps, etc.)
- Detect energy level below threshold for notification of load not running (septic pump, fridge, freezer, etc.)