Drupal - drupal.org, & Assorted Links
drupal.org - http://drupal.org
Day-One Users - Warning - This site is a 'trainWreck'Twitter - https://twitter.com/drupal_org
Answers - http://drupal.stackexchange.com/
Association - https://association.drupal.org/
Association: Tracker - https://association.drupal.org/tracker
Forum - http://drupal.org/forum
Glossary - https://www.drupal.org/docs/7/understanding-drupal/glossary
Groups - https://groups.drupal.org/
Groups Tracker - http://groups.drupal.org/tracker
Modules - https://drupal.org/project/modules
- D7 Modules - Search by 'Relevancy' drupal.org/project/modules?filters=drupal_core%3A103&text=%20
- Module Usage Chart
Themes - https://drupal.org/project/themes
Releases
- Releases for Drupal core: https://drupal.org/node/3060/release