Have you heard of the Great British Refurb? It was a competition launched across Great Britain a few months ago to give an old existing home an eco makeover. The winning house in Bristol, England, was chosen from over 8,000-plus entries, and this video shows what was done to bring the home into the green age: think insulation, upgraded double glazing, a voltage reduction device, klick taps to reduce hot water usage, chimney "balloons" to reduce air infiltration, and a state-of-the-art solar PV system worth about $19,000 USD.
As TreeHugger says, new LEED homes are well and good, but with so many homes and buildings already in existence, we need to find ways to make those homes more energy-efficient. This is an extreme example, but it's cool to see what can be done.