Keith McCafferty shares instructions for sharpening your knife so sharp you can shave with it. I would think this could be handy knowledge in a lot of scenarios and even right in the kitchen. This is something I used to watch my grandfather do. I have an electric sharpener but if you were in the woods or without power at least after learning how to do this you could still sharpen a knife.
http://www.fieldandstream.com/articles/hunting/2011/05/outdoor-skills-hone-knife-sharp-enough-shave
