I started building my own power cords using Venhaus shielded twisted pair 12 gauge wires. I then used their Flavor 3 design.

If you'd like to see visually how much energy is transmitted outside of a power cord, just get your self a Greenlee Non-Contact Voltage Detector(I believe that's the name). It is a small, battery powered probe that detect AC voltages starting at around 60 volts AC. When it detects one, the led lights up and it emits a high pitch tone. When I use the Flavor 3 cords, there is no detected voltages, though I can pick up a voltage within a few inches of an unshielded power cord. So, whatever devices I have that use a detachable power cord, I've replaced with the Flavor 3 variety. The only complaint I have is that the Venhaus cables are pretty stiff. I don't go overboard on the high dollar plug ends.