If you're a writer looking for tools to help you keep your ideas and thoughts together in one convenient place while you write you have two pretty good choices. First is Storybook, which is an open source creative writers tool that helps keep all the details, like characters, places, research and plot-lines, easily at hand while working. Celtx is another with similar features. Celtx is freeware and has commercial plug-ins, which were not really needed, but may enhance the core product. Celtx supports many nice features and can be used for many types of writing including scriptwriting and comics.
Celtx (OS X, Linux, and Windows)
Storybook (Windows and Linux)
