Geothermal heat pumps...
Installation costs from $10k to $18k for a "normal" house.
If someone is spending $400 a month, five months a year, for heating oil then you're looking at a 5 to 9 year payback. After that heating costs will be minimal.
And you'll be protected from rising oil prices.
Same thing holds for someone paying major bucks for AC during the hot season.