Today’s invention is the transparent plugtop.
This allows the interior of an electrical plug to be viewed, so that a user can check that the wiring is correct before plugging in the attached appliance (there might even be coloured lines on the plug’s inside surface with which the wires could be compared).
The fuse rating could also be easily seen as well as any internal scorchmarks or cable fraying.
This could be incorporated in new plugs or as a replacement for existing plugtop front plates.
Nice idea. It would extend the iMac design style rather usefully.