You do realize that you are almost literally playing with fire here, right? I mean, there is a REASON why the plugs are incompatible. The power systems are not always the same, in fact they are RARELY the same or even compatible. So sure, you can find SOME devices that accept a universal input, because many electronic things now have what are called Switched Mode Power Supplies that just convert AC to DC, and can be easily made to accept a wide range of input voltages and frequencies. But that is only SOME devices, and if you make a power strip that allows Susie Homemaker on a trip to the FIFA World Cup to plug her 115V 60Hz hair drier into a 230V 50Hz socket, and the blow torch that it becomes catches her hair on fire, your dreams of riches will go up in smoke with it.
"Will work for (the memory of) salami"