Electric toasters work great, but they suck up a lot of electricity. In most parts of the world, electricity is one of the least cost effective ways of generating heat. Burning either natural gas or propane is generally much cheaper.
I propose a pop up toaster, powered by flammable gas (natural
gas, propane, hydrogen, syngas, etc..)
It would have a slot in the top for the bread to be put into, and two infrared burners, each mounted vertically, to toast the surfaces of the bread. It would also of course have a timer and a mechanism to pop the toast up when done.
Since infrared burners burn very hot, the toast could be done very quickly... as a plus, we'll never have dry toast, but on the other hand the timing mechanism would need to be very precise.