A friend asked me about mind mapping programs. These are programs that help with brainstorming and outlining ideas. Since I last looked into these programs, they've all become cross-platform, which is nice to see.
The standard, I think it's safe to say is MindManager.
A simpler and more visually pleasing program is called Nova-Mind.
And the third one, also cross-platform, is Inspiration. Their website is oriented at schools and kids, but don't be put off by this: the product is very good. It's the least complex of the three and I find it to be sometimes the easiest choice for created the easiest maps.
Though Inspiration maps aren't as visually pleasing as NovaMind nor is the program as powerful and extensible as MindJet, I find it easiest, often, to create what you visualize.