vym - VYM (View Your Mind) is a tool to generate and manipulate maps which show your thoughts.
Xmind - Xmind is a brainstorming and mind mapping application.
Linked Ideas - A macOS/iOS apps to treat ideas as links of concepts.
MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.
Freeplane - Freeplane is a powerful and free software for building mind maps.
MindManager - With MindManager, flexible mind maps promote freeform thinking and quick organization of ideas, so creativity and productivity can live in harmony.