I love this idea. This video by Rob Hansler shows some great pointers on how to make a self feeding fire with materials you can find around you in the wilderness including how to get it started and ensuring that it keeps burning strong. As you can see in the picture, the two ramps will continue to self feed the logs as the fire burns.
This is an efficient way to build a fire that will burn continuously and does not require ANY maintenance. This is also an excellent method to utilize if you need the heat from a fire while you are sleeping, but do not want to wake up repeatedly during the night to add more wood.
In an emergency situation this could be a great advantage to know this way of building fire so you get a restful nights sleep ready for the next day. The key is to get the angle correct so that the logs feed into the fire. He also shows you how to build a soil bank to control air flow and keep the logs burning evenly. Check out the video below.