Give your WordPress site forums, activity streams, groups and more with the free bbPress and BuddyPress plugins.
All within your browser, Aegir lets you add new Drupal sites, clone or backup or delete existing sites, manage "platforms", and much more.
Learning Drupal can be much more interactive than wading through the docs on drupal.org (though they do tend to be excellent). Check out these awesome Drupal resources.
If you administer Drupal sites, you need to learn drush, a command line Drupal management tool. Drush "makefiles" are especially powerful and time-saving.
Imagine if you could reduce your Drupal site or platform to a simple "recipe" of exactly which modules, themes, and libraries it required. Intrigued? Meet drush makefiles.
You know about Drupal "modules" and "themes", but how about those mysterious directories in "sites/all/libraries"? And why do you have to download libraries separately?
Avoid breaking your Drupal site by understanding how modules depend on each other.
Need a newer version of jQuery than the version that comes with Drupal? Here are multiple possible solutions.