In article <iNHHh.44937$3a3.13118@newsfe6-win.ntli.net>,
Bogwitch@reply.to.group.fake says...
>
> I doubt a big magnet would have an effect on a flash memory stick.
>
> It would be possible to create a high voltage USB socket fitted with a
> large panic button. You could hold the usb memory device in that and if
> the panic button is depressed, the memory chip can be destroyed. You
> would have to mess about with getting the voltages right and probably
> write off a few keys in the process. It is possible tha memory devices
> are protected by buffer circuitry to prevent damage in such an event, as
> I said, experimentation would be required.
>

And unfortunately the circuits around the memory cells would burn out
long before current hit them leaving the memory possibly damaged
but maybe readable to any agency capable of moleculare diagnosis. (i.e.
Any government or large corporation)
Magnets - even large powerful ones are no use against any media - even
floppy disks. You'd be amazed at how resiliant magnetic domains an be.
Grinding such devices into very fine dust is probably the safest bet.
I cant think of a single way to quickly ensure they are safely wiped from
really determined or well funded recovery.