I'd heat water with it but have yet to find an effective and efficient means to do so with wood or paper.
Back when we had an electric hot water heater we just built a metal reservoir into our wood stove and plumbed it into line with the cold water feed to the heater. The heater still functioned normally, but whenever we were heating with wood the input water was already at temperature and the tank would only have to maintain (or slightly heat) the input water.
Its a start, and not hard to hack into your existing setup. What we had was pretty simple, but knocked a huge chunk from the electricity used by the heater. I don't think you'll find a good way to use paper/wood as the primary source of heat, but as a secondary that does most of the lifting you'll find a lot of options.