Alan Meany's Ambient Knowledge
Check out Alan Meany's Ambient Knowledge energy monitor project using the non-invasive Mains AC method, its a really nice idea, from Alan's website:
"Ambient Knowledge is a lamp that glows different colours to display the current consumption in your home. Ambient Knowledge is an Ambient Energy Information Display that provides you with energy information in a visually pleasing, easily accessible convenient, glancable manner. At a quick glance AmbientKnowledge will make you aware of how much energy your house is consuming in a subtle simple approach, with minimal effort needed."
Alan will be exhibiting Ambient Knowledge at Ars Electronica 2010 in Linz, Austria 2nd - 11th of September.