A few issues ago, I discussed mind mapping tools - software that allow you to create, edit, and modify a graphical model of interrelated ideas so that you can explore an idea or topic for writing or documentation purposes. And, of course, as we're interested primarily in Web applications all of the tools we discussed were capable of exporting maps to HTML.I just found out about another mind mapping tool that has several very interesting features not the least of which is that it is open source and free. The tool, called FreeMind (see links below), is easy to install and use and comes with really great documentation of the source should you want to make any changes.FreeMind, written in Java (requires Java 1.4 or higher), is a work-in-progress but is very stable at its current release level (Version 0.61) albeit a little slow in some operations (file access seemed to be unusually slow although I can't guarantee that there aren't any issues with my PC configuration).Eschewing the overblown user interfaces of similar products FreeMind is very easy to use. It features:* "Fast one-click navigation," which allows folding and unfolding subtrees and following links with a single click.* "Smart Drag'n Drop," which includes copying nodes and node styles, working with multiple selected nodes, dropping text or lists of files from other applications.* "Smart copying and pasting," which includes pasting of links from HTML, pasting of lists of selected files, and pasting plain text and RTF content.FreeMind allows for a styling nodes and connecting lines with predefined styles or custom colors, node outlines, line width and styles, text styles, text colors, and so on. Curiously, the current project manager, Daniel Polansky, comments in his list project weaknesses that the maps have "Poorly looking main branches, especially when compared to commercial alternatives, no support for fancy graphics." I have to disagree - I find the presentation very acceptable.Nodes can include URLs of any kind and can be created from your browser favorites list or from the file list of any local subdirectory structure.FreeMind can be run as a desktop application with full editing abilities or as - and this is really cool - a browse-only applet downloaded from a Web server (all links in nodes will work except, of course, for previously created local file system links). You can also export mind maps as HTML pages that include "folding" - the ability to collapse sub-nodes under a parent node.Saved maps are in an XML format which makes it easy to convert into other formats for other applications or to generate maps from other applications (this could be particularly useful on a Web site).Outstanding!