XMind

The world's coolest brainstorming and mind mapping software and the best way to share ideas. XMind is a great brainstorming tool. With XMind, you can just double-click to create and edit topics anywhere on the map. Drag-and-drop for reorganizing topics, moving markers, taking a mapshot, and adding attachments. You can even search on topic with Google and drag images into your map without leaving the working window.

XMind's intuitive design and powerful features let you focus on your work and share it easily with others. You can export maps into a variety of popular formats such as PDF, Word and PowerPoint.The software is an Open Source Awards winner. Xmind is the best Eclipse RCP application 2008 in the Eclipse community, and the best project for academia 2009 in the SourceForge community.

This version is free. There is a pro version with more features available for $49/year