I have been using OmniGraffle to map out and conduct our Dungeons and Dragons sessions at work. So far this "kit" is just a simple stencil and a template, but I have some grand ideas for troves of resources like different tile sets, room debris and tavern tables and treasure and so on. If you have any feedback or contributions, write to jet fuel at metal bat dot com. :D
Also check out the character sheet, power cards, and improved attack workspaces our group has created for OmniGraffle.