So, I'm elbow deep in the guts of my first 'book'. I have a world that my characters inhabit and have the bones of some decent characters that I can start fleshing out as the story progresses. I also have the overall arch that I want the story to follow. I am however getting a bit worried that I wont be able to hold all the plot threads together. What I really need is a decent map to help me keep track of places and I was wondering if anyone here knew of a decent but free tool to design a map with?