Story boards, they are good things. The week leading up to our first day of filming I have spent quite a bit of time doing story boards of the scenes. A story board helps communicate the shot and scene to everyone, the cast and crew. It helps save time on the set (especially on green screen), and help avoid mistakes. If 2 shots don't work well on the story board, they probably won't in the edit sweet either. It also helps avoid problems such as crossing the 90o rule. Needless to say, I don't story board very much; I usually have such a tight schedule, that even if I had time to make them I probably wouldn't have time to show them to anyone (and I am the whole crew anyway). However, for this protect we budgeted enough time for story boards. Story boards are useful for actors. Specifically when on green screen, they can see what the shot is going to look like, what they are looking at, and what the other actors are doing (who are not even there that day). It has already paid off, too. On our last project, The Amazing Map, our actors really had no idea what they were talking about (you can't tell that by the final video). On this project we decided that it was important that our actors knew what was going on around them. There is a lot more drama and such in this video. So on shoot day, we sat them down and whet through the story boards, having them read their lines as we looked at the shots. This allowed them to gain an understanding of what was happening in the story of the movie.
Of note, Celtx has a built in Story board manager. It has quite a few things to be desired, but honestly I have yet to find a story board program that I like the looks of, even the ones you have to pay for. Either they don't have built in drawing tools, or are 3D and either make ugly looking output images, or are overly complicated.
I did my story boards in The Gimp, using the pen tool to give the lines some "life". I hate the way my hand drawn images end up looking. If I have to keep looking at something all day on a shoot, I want it to be ascetically pleasing.