Freeplane

Freeplane is a free and open source software application that supports thinking, sharing information, getting things done at work, in school and at home. It provides you a set of tools for mind mapping (also known as concept mapping or information mapping) and navigating the mapped information. Freeplane's capabilities will appeal to power users, but for the typical user is also a more robust alternative to Xmind, Mindmeister, and similar mind mapping software. Freeplane is written in Java using OSGi and Java Swing. It runs on any operating system that has a current version of Java installed. It can be run locally or portably from removable storage like a USB drive.