One thing has been bugging me about the macbook laptop power supply for a while. For those who aren't familiar, the power supply has a removable input, allowing you to have a long cord, or a direct power plug aka wall wart. The long cord has an earth connection, however the short plug does not.
Consequently the chassis of the macbook is at around 96V AC with respect to mains earth. While the actual surface of the laptop is powder coated with an insulating coating, touching the surface AC couples you to the voltage, or even a metallic object placed on the chassis. As best as I can measure, about 130uA AC will flow from whatever is touching the chassis to earth.
I suspect there are spikes in there too, as depending on what nerves the current flow through, there is a significant stinging or burning feeling.
For the premium price that is paid on the product, I would have thought they could do a 3 prong short plug too, or a different design in the psu. Hell I don't even like the thinness and miniaturisation fad. Ill carry around a bulkier unit if it performs well.