gksu is a Gtk+ frontend to /bin/su. It supports login shells and preserving environment when acting as a su frontend. It is useful to menu items or other graphical programs that need to ask a user's password to run another program as another user.
nautilus-gksu | privilege granting extension for nautilus using gksu | Mehr ...
The gksu extension for nautilus allows you to open files with administration privileges using the context menu when browsing your files with nautilus.