Edit: The XPath Visualizer for IE now has a new, safer home, thanks to the kindness of Lars Huttar. Also there is the XPath Visualizer for FF.
The XPath Visualizer has been available for more than 10 years and has helped thousands of people learn XPath the fun way. Available for IE and for FireFox.
The XPath Visualizer is a popular tool for learning XPath by playing with XPath expressions. Free and open source.
Allows any XPath expression to be evaluated against a given XML document and displays the results hi-lighted in the xml document (if they are node(s)) or in a separate box (if the results are atomic values).
Allows xsl:variable-s to be defined and then used in XPath expressions.
Allows xsl:key-s to be defined and then referenced by key() functions within XPath expressions.
