For posterity I came across this post on CFCDev when dealing with an xPath issue:

Tools:
http://sourceforge.net/projects/xpe/ - Xpath Explorer
http://www.topxml.com/xpathvisualizer/ - The XPath Visualizer Version 1.4
Tutorials
http://www.w3schools.com/xpath/default.asp - W3Schools XPath Tutorial
http://www.topxml.com/xsl/default.asp - Learn XSL & XPath Tutorial
Book
http://www.oreilly.com/catalog/xpathpointer/ - XPath and XPointer