Plot Factory - Online story planner, organizer, and writing application.
Xmind - Xmind is a brainstorming and mind mapping application.
World Anvil - World Anvil is a worldbuilding tool for Authors, Storytellers and worldbuilding lovers.
Mindomo - Easy-to-create and share mind maps, concept maps, task maps and outlines. Mind mapping software for Web, Desktop, iOS and Android. Mind map with us for free!
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.