1. Most ordinary appliances --

For most appliances you need an autotransformer. These are readily
available in ratings from 50W to 1000W and more.  I have a couple of
nicely packaged units with a flying lead for the input and a USA style
power outlet.  They are fully reversible too, you can use them to
convert voltage in either direction.  A Variac will also work.

2. Appliances with induction or synchronous motors --

If motor speed is critical you will not appreciate the 20% speed up
on 60 Hz mains.  At least you won't have the problem we sometimes have
in Europe where a 60 Hz motor will overheat when run at 50 Hz due to
magnetic saturation.  There may be sophisticated bits of electronics
to convert 60 Hz to 50 Hz but I do not know of any.  One answer is to buy
a sine wave inverter of adequate rating.  These normally take 12V or 24V
input which you can supply from a suitably rated battery charger,
possibly smoothed by a small lead acid battery.  Incidentally, this is
a home-made uninterruptible power supply too.

I once made a variable speed drive for a small motor using an audio
amplifier driven from a variable frequency oscillator.  The amplifier
I used had a 100V line output for public address work, this nicely
matched the 110V motor I was using.  Otherwise I would have used a step
up transformer, also known as an ordinary transformer used in reverse.

If all this is too much trouble it may be easier to use a smaller pulley
on the motor.

Jeffrey Borinsky, London