Our house has four-zone gas hot water baseboard heating. If things get cold enough (and they were), we can get frozen pipes, a messy and expensive problem. Also, some of the lowest zones appear to be hard to drain: the spout is two feet above the lowest run of pipe.
It has occurred to me during other, much shorter power failures that we really ought to be able to have heat in the house, given just a little bit of power. We still have the gas supply. The four circulator motors don't have to lift the water, just move it around. In fact, they are 1/15 HP, using about 75W. The furnace is electric start, so it needs a little as well.
I went to Walmart and bought a 750W inverter. This I clipped to the battery terminals of our idling Miata. I disconnected the furnace power from the mains and connected a 3-conductor wire with plug to it. It was definitely not up to code, but it was reasonably safe. I plugged in the furnace via extension cords, and the furnace fired right up. We had a warm, comfy, dark house, with enough spare power to charge batteries, run the DSL line and a laptop, and even turn on our outdoor LED Christmas lights ("survival with style").
I tried charging the UPS for our regular computers, but it complained loudly about wiring faults in its supply. I suspect that the inverter either doesn't have ground hooked up usefully, or the UPS had some complaint about the modified sine wave that the inverter generates.
The Miata was fine. The guys on Car Talk point out that cop cars idle for long periods of time without harm: we aren't using carburators any more. It got zero miles per seven gallons, more if I ran hi-test.
This all worked well, but it was a long haul. This was the first major outage we've had since moving into the house in 1991, so it probably isn't worth thinking about getting a generator.
I wish I had a small natgas fuel cell (or even a large one). We had an ample energy supply, just not electricity. Home fuel cells could mitigate a lot of potential problems for society.