I was riding along, and heard a guy yelling.  I found him, and he had been bit by a snake.  The options were to suck out the venom, or give him a health tonic.  I gave him the tonic and saved his life.  A few days later, I saw him at the gun smith in Valentine, and he allowed me to go into the gun smith and pick any item in the whole catalog for free!  Guns and all were listed at $0.  It was awesome!