Visual Understanding Environment - Visual Understanding Environment (VUE) is a mind-mapping and concept-mapping tool.
Rationale - Rationale let's you create, online, argument maps.
Flying Logic - Highly visual software for planning support used by strategists, process improvement specialists, teachers, and writers. Windows, Mac OS X, and Linux.
ThinkComposer - Software for create adaptable and multilevel diagrams, concept maps, mind maps and models
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.