WordPress from the command-line (Linux, Mac, Windows, BSD, Solaris, etc.)
Don't log in to the dashboard on 20 sites one after the other; just type one command.
Automate everything and use many bonus tools (e.g. automated backups, maintaining custom patches and version control). This is the time-and-money saver that WP admins have been waiting for.
Example commands:
wordshell all --listupdates --everything wordshell all akismet --update --latest wordshell mysite contact-form-7 --rollback='2 days ago' wordshell site1,site2,site3 --update --core --latest wordshell nextgen-gallery --changelog --description wordshell mysite --login wordshell all --database --listrollbacks wordshell mysite myplugin --showchanges