Useful resources
The following are some useful resources for us to further our learning and understanding of the Drupal module system:
Drupal 7 Module Development: https://www.packtpub.com/drupal-7-module-development/book
Beginner's Guide to Drupal 7 Fields: https://www.packtpub.com/drupal-7-fields-cck-beginners-guide/book
Drupal 7 API: http://api.drupal.org/api/drupal