Large parts of the world actually live that way, and Aprovecho Research Center (www.stovetec.net) decided to help improve the situation. In the process, they came up with what I believe is a great survival stove. It burns wood or charcoal (or roots, crop residue, or other dry biomass), so you can operate it on twigs, scraps of lumber, bits of charcoal or other combustible materials. It has handles that make it easily portable. And my tests demonstrated that it is very efficient — the fire starts quickly and burns vigorously on very little fuel. Air flow is controlled by via a sliding door below the combustion chamber.
The stove was invented by Dr. Larry Winlarski, in an effort to provide impoverished populations with a better way to cook. The unit is designed with an internal clay brick chimney that focusses the heat up through a narrow channel, unlike an open fire that allows the heat to dissipate in all directions.
The Wood-Charcoal model ($40) allows you to burn sticks that rest on the fuel shelf and get pushed into the fire as the burning end is consumed. If you're using charcoal, it is loaded into the combustion chamber and ignited from above. The metal ring on top is a pot skirt that improves efficiency.