Following are links to training resources for beginners and experts alike.
SI505 - http://si505.cms.si.umich.edu/
- Customization and Configuration. Resources for a course at the University of Michigan taught by Paul Resnick.
Drupal Dojo - http://www.drupaldojo.com/
-A very active group sharing knowledge of Drupal. A great place to start!
Drupal
handbooks - http://drupal.org/handbooks
- official Drupal documentation
screenshots - http://drupal.org/image
-Installations, themes and site examples
videocasts - http://drupal.org/node/63155
- module mash-ups and solutions
Drupal 5 Resource Center - http://drupal5.cei.psu.edu
- Notes, solutions and issues documented by Michael Hofmockel
IBM Drupal guide - http://www-128.ibm.com/developerworks/ibm/osource/implement.html
- A wonderful documentation of developing and deploying entirely with open source software.
Lullabot - http://www.lullabot.com/
- A Drupal consulting company that posts Drupal related articles.
Chapter Three - http://chapterthreellc.com/
- Another Drupal consulting company that posts Drupal articles.