It seems to be an annual event of people nicking your idea...I've just seen this one:
http://tiphero.com/flower-pot-heater/
it obviously produced no more heat than the four candles but it spread that heat over a greater volume of air and seemed to eradicate the cold spots around my feet
Lets remember they do give off carbon monoxide and use up Oxygen so could kill you if used in a small enclosed space ...ie a boat ! so if used there MUST be ventilation.......In fact is it a Silly idea in a boat?