Drush (DRUpal SHell) for Drupal is a command line tool that allows users to perform most of their administrative actions from the terminal as opposed to going through the Drupal administrative pages.
I have been using drush for a while and I can definitely say that it has changed the way I manage and build my Drupal sites and then, I discovered drush_make. Drush_make is an extension for drush that gives admins extra power in allowing them to create Drupal (and Pressflow) build-outs rapidly by using a .make file that lists all of the components required and then downloads and installs them for you.
