Freeplane is a powerful and free software for building the mind maps. It is a redesigned version of the well known FreeMind, and is created by one of FreeMind's key developers
Manage your bookmarks and notes anywhere! Simple, extensible and easy-to-use Web-based bookmark management and tree UI tool. Bookmarks are stored as text files and managed with PHP. Javascript-based keyboard navigation. MarkTree is released as Open Source (MIT/X).