The Drush Project Manager allows you to download, enable, disable, uninstall, update modules/themes/profiles/translations from the command line in a very simple way (apt-get style) - just type e.g. drush dl views and drush pm-enable views in a Drupal directory to install the Views project! Additionally, the Drush Package Manager also allows you to update all your modules and even Drupal core with just one command - drush pm-update.
Drush Core: several useful utilities for site administrators and developers (e.g. drush cron or drush cache-clear). Also includes a customized bash shell for drush. Start it with the drush cli command.
Drupal SQL Commands help you issue queries to any of your databases (i.e. is multi-site aware) and even helps you migrate databases between your environments.