I would call myself an advanced amateur at hardware/software solutions for home energy management. I experiment with various ways to remotely monitor sensors and I am particularly interested in ways to make it affordable and meaningful to track energy usage, down to the appliance level, within a residential environment.
My current system uses three power sensors and one temperature sensor (solar powered), all wireless using the zigbee protocol. They are polled by a low power gateway device that sends the sensor readings to a data logger service where the information can be charted and analysed. Cost of parts, $250.
I plan to expand the system to include indoor quality of air sensors, SMS alerts, and the ability to control the sensor devices and appliances from a secured centrally web portal.
Others are doing this, but most track whole house and are relatively expensive and are better suited to commercial buildings or high end residential homes.
We'll see how this goes...