KShutDown is an advanced shutdown utility.

Features:
  o Turn Off Computer (logout and halt the system)
  o Restart Computer (logout and reboot the system)
  o Lock Screen (lock the screen using a screen saver)
  o End Current Session (end the current KDE session and logout the user)
  o Detect user inactivity/application exit
  o Command-line support
  o Extras (custom actions)
  o Simple, easy-to-use User Interface
  o Works with many Desktop Environments
  o More than /sbin/shutdown -h ;-)

WWW: http://kshutdown.sourceforge.net/