To be honest, I am not sure which is a better way to ask the question: Is gold an acceptable means of currency exchange in most travel-able countries? or which countries is gold NOT an acceptable means of currency exchange?
This question comes to mind in respect to backpacking across Eurasia. I know most European countries take gold, but I have little knowledge on topic from Eastern Europe on to the eastern coast of China.
The idea is that gold carries a lot of value with very little displacement and weight. With gold at it's current value, one could feasibly carry a few ounces to finance the trip.