Ben Arent, a creative young designer, has proposed the EnergyTree. Basically it's an actual tree that is connected to a processor that monitors your in-home environmental habits. And depending on your energy/recycling routines you will either feed your baby tree water & nutrients or poison. That's right, if you are bad to the planet you will see the effects in your very own home, as your tree begins to die.
Currently the EnergyTree is only a concept, but it's entered in Microsoft's StartSomething PC design competition. So hopefully we will see it make its way into production, because we currently have no idea if keeping our office at a crisp 65 degrees is outweighing our gadget power consumption.