For those concerned about climate change or dependency on foreign energy, a home geothermal heating and cooling system may be just the ticket. Such systems take advantage of how the temperature is relatively constant underground, whether it is overly hot at the surface or overly cold. As such, it can be used to heat in the winter and cool in the summer, while using only a minimal amount of energy to carry out the heat exchange. While this is a pretty expensive thing to install in a single existing house after the fact, it seems plausible that it could be scaled in ways that make it economically viable in a good number of environments.
If electricity, oil, and gas really started to get expensive, you would start seeing a lot more such systems. Another example is the pipelines that draw cold water from the bottom of Lake Superior to cool office towers in Toronto during the summer.
Conservation may not be as technologically engrossing as genetically modified biofuels and hydrogen fuel cells, but it is definitely a proven approach.