Views XML Backend is a Views 3 plugin that adds native XPath 1.0 query generation. It allows you to parse XML/(X)HTML with XPath selectors using Views' graphical query builder.
* Views 3
* The module comes with two example default views, the XML for project releases and the RSS of the Drupal Planet.
* Views Rules also has an RSS ~importation example in #1650604: Example and/or video.
* Feeds XPath Parser's documentation includes a lot of general information on using XPath.
* dmitrig01's D6 XML Views screencast demonstrates the same basic workflow for creating views of XML data.