The 100+ year old house I'm in has most of the original hot water radiators. Originally coal fired boiler (found remnants of old coal chute during a renovation a few years ago), replaced with oil fired at some point. Boiler (Weil MCLain Gold series) only a couple years old when I bought the place, but cost of heating oil has me REALLY wanting to convert to gas fired boiler. Already have gas in the house for water heater, dryer, and range. Not sure why the previous owner never converted over.
Beyond the fuel cost savings, I would love to be able to expand my basement electronics lab into the space taken up by a big metal oil storage tank.
Replaced one old cast iron radiator with hot water kickspace and baseboard heaters when I redid the kitchen a couple years ago. They work very nicely with the old radiator piping system.