From the I didn’t know I needed this department comes ASCIIFlow.
Are you tired of having your diagrams being fancy? Would you like to go back to a simpler time of diagramming, where you only need a hyphen, plus sign, or capital X? Then ASCIIFlow is for you.
I could see this being used to draw up simple graphs for emails (be sure to use a monospaced font such as Courier New or Trebuchet in your email) or a way to draw the map to your hidden treasure, and let X mark the spot.