A free mind mapping tool
Taking the Concept-Mapping approach to Human-Computer Interface design. A mind mapper, and at the same time an easy-to-operate hierarchical editor with strong emphasis on folding. These two are not really two different things, just two different descriptions of a single application. Often used for knowledge and content management.
FreeMind doesn't work with classpath based Java implementations. Use OpenJDK (or Sun's Java), and check freemind(1) for more information.