Visual Understanding Environment - Visual Understanding Environment (VUE) is a mind-mapping and concept-mapping tool.
Xmind - Xmind is a brainstorming and mind mapping application.
MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.
FreeMind - FreeMind is a premier free mind-mapping software written in Java.
MindManager - With MindManager, flexible mind maps promote freeform thinking and quick organization of ideas, so creativity and productivity can live in harmony.
yEd - yEd is a free desktop application to quickly create, import, edit, and automatically arrange diagrams. It runs on Windows, Mac OS X, and Unix/Linux.