Xmind - Xmind is a brainstorming and mind mapping application.

Scrivener - Scrivener is a content-generation tool for composing and structuring documents.

MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.

SuperNotecard - Introducing SuperNotecard. SuperNotecard is an online writing tool that features virtual notecards to help arrange facts or scenes, track details, organize paragraphs, and clarify your composition process.

Coggle - Coggle is a simple, beautiful, powerful way of structuring information.

Pencil Project - Single-user mockup / wireframing / diagramming tool