Map your Mind Free Of Cost With XMInd

XMind is a opensource MindMapping Software ussed to generate, visualize, structure, and classify ideas,and as an aid in study, organization, problem solving,brain storming, decision making, and writing.
XMind 3 provides the following features

• Mind Map
• Fishbone Diagram
• XMInd Spreadsheet
• Markers
• Inline Notes
• Hyperlink /Attachments
• Topic As A Map With Drill Down Facility
• Spell Checker
• Legend and Filtering
• Compatible with Freemind/MindManager files meaning Import from Freemind/MindManager supported
• Export to Html/PNG/GIF/JPEG/BMP
• Online sharing and collaboration via XMind Share

XMInd Pro 3 is priced at $49.00/year or $6.00/month and has the following additional features in additioan to the XMInd 3 features (Described above)

• XMind files can be used for Presentation in Presentation Mode
• protecting the XMind files through password
• Gantt view
• Export maps into a variety of common office tool formats such as MicroSoft Word, PowerPoint, PDF, or RTF
• Allows to export your .xmind files into MindManager maps and/or FreeMind Maps.
• Search Topics/Images from web within XMind
• Improved Collaboration (Share Privately,Mapshot,Map Merge)
• TaskInfo
• Gallery

In addition to these it has a plugin for Eclipse-based enterprise environment.
XMind is dual licensed under two open source licenses:EPL and LGPL.
Some of the other free MindMapping softwares worth looking are Compendium ,FreeMind, Pimki, WikkaWiki, VUE