Someone posted this link recently and I thought it looked like an
interesting approach:

http://www.chilipepperapp.com/

If you click around the website it explains the whole system in detail, how
it works, etc.

Steve wrote:
ok, my source of heating my domestic hot water is a oil fired hot
water radiation furnace system.

my problem is it takes way too long from the time I turn on my hot
water taps to the point where i actually get hot water. The furnace
has to turn on, water has to flow though the coil in the furnace and
then flow upward to my taps. What I want to do is put in a
non-heated storage tank (about 40 gallon) right after it comes out of
the furnace. So when I turn on the hot water taps, it immediately
comes from the storage tank, as it gets filled by the hot water
coming from the furnace.
The tank would obviously be insulated very well to keep in the heat. Temp
of water going into the tank would be about 180-190 degrees.

Does anyone see any problems with this setup? Have any suggestions or
comments? I'm just throwing this idea out there.

My storage tank is an old oil fired hot water tank.

Thanks,
Steve Cornick