Byung-seok You is a smart, smart man (or woman?). He (she) has invented an amazing device that I can't believe hasn't been thought of before. It is a ceramic "plate" that is formed to fit on top of your standard household radiator. The heat from the radiator heats up the plate and you can put your coffee, pastries or sandwiches there for a warm up.
Pretty ingenious really. Did I mention that I want one?