Sometimes phantom power has a legitimate use. DVRs, for example, operate at a minimal level of power when not in use so as to keep track of which programs to record. Other instances of phantom power, however, are simply wasted electricity. Cell phone chargers use nearly as much electricity when plugged into the wall by themselves as they do when actively charging your cell phone. If all SPU students living on campus left their cell phone chargers plugged in 24/7, the chargers would consume the same amount of electricity annually as three houses.
The best way to vanquish phantom power? Unplug electronics when you aren't using them.