>> > What's about a light source (light-bulb connected to AC) and some
>> > solar-cells ?  :-)
>
>Now for my own wacky idea: microwaves!  Use old uwave oven magnetron,
>transmit down waveguide (or between parabolic reflectors for that
>megavolt isolation), receive in 1/4 wave antenna and rectify using a
>swag of hot carrier diodes.
>
>Back to reality, another way of obtaining galvanically isolated supply
>is with piezoelectric 'transformers'.

Let's not forget the dynamotor: an ac motor driving a DC generator.  For
extra isolation, use a rubber belt to connect the two.

And has anybody tried an AC fan driving a windmill connected to a DC generator?

Or an AC powered Gerbil running in a wheel connected to a DC motor?