Heat pumps and stuff
"If you've not got the space, or the geology for ground source heat pumps, then air-source heat pumps are probably a good solution. I'm told you can achieve about 3 watts of heat, for every watt you put in. I think kit isn't too expensive. Though quite large."
Air source heat pumps are very popular now in New Zealand - the climate is just right for them (since few places drop substantially below 0 celsius). They are efficient (~300%), and do make a huge difference. I know people that have decommissioned gas fired central heating systems and retro fitted heat pump systems and seen winter energy bills halve whilst maintaining a warmer house. They are substantially cheaper than ground source heat pumps (around NZ$3500-4500 for a single unit for a typical house, or $8-12K for a fully ducted system).
Reverse cycle hot water heaters are also dropping in price (working on the same principle as the heat pump), and I believe at the moment these work out at a similar cost to a solar hot water heater over the typical life of the unit.
Widespread local energy generation where sensible (like solar hot water), coupled with efficient heating (like heat pumps and wood pellet burners) along with clever design (like Passiv Haus designs) could make a substantial difference to grid energy draw by households.