Scapple - Scapple is an easy-to-use tool for getting ideas down as quickly as possible and making connections...
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.
vym - VYM (View Your Mind) is a tool to generate and manipulate maps which show your thoughts.
SpiderScribe.net - SpiderScribe.net is an easier and more flexible way to create mind maps and brainstorm online.
Freeplane - Freeplane is a powerful and free software for building mind maps.
MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.