once you are getting familiar with XPath and XMLStarlet, you are using it for rather “ordinary tasks”

• http://xmlstar.sourceforge.net
• https://www.cygwin.com – “Get that Linux feeling – on Windows“
• https://cygwin.com/cgi-bin2/package-grep.cgi?grep=xmlstarlet
• http://www.finkproject.org – “The Fink project wants to bring the full world of Unix Open Source software to Darwin and Mac OS X. …“
• http://pdb.finkproject.org/pdb/package.php/xmlstarlet

Areas, where you will want to make use of XPath expressions and xmlstarlet in order to extract details:

• HTML web pages – if only more of them were proper XHTML! but xmlstarlet can even help you “tidying” improper HTML
• RSS feeds and esp. podcasts – listing all the MP3 files referred to within the feed
• various XML files …