How about relatively small BTC mining room heaters - plug them into an electrical supply they provide heat and offset the heating costs with returns from mining?
As it happens I was actually offered a Xerox Lisp Machine to take home when a university department I was associated with was throwing some old kit out. I was living in a tiny flat at the time so it wasn't really an option.
However, now we have plenty space and a property that is very difficult to heat and we need heating ~6 months a year, changing the property is not really an option (planning restrictions are really tight where we live - for good reasons, and any improvements would be incredibly expensive) - BTC room heaters might actually make sense....
The linked article touches upon that concept as a feasible application of mining heat:
"In a home, however, if the outside temperature is less than about 20′C, the cost of electricity is zero; all electricity spent by the miner necessarily eventually turns into “waste” heat, which then heats the home and substitutes for electricity that would be spent by a central heater."
The zero-cost figure is... um... wrong. Your central heater probably either does not use electricity (presumably using a cheaper fuel source) or is a heat pump (and thus gets efficiency greater than 100% on the electricity by stealing heat from the ground). The real cost is still lower than the nominal cost, but it's not zero.
Edit: I was being ~70% serious about this...