GShutdown also allows you to set the date and time or time from now that has to pass for auto shutdown to be initiated and it can initiate auto restart or logout (end session) as well. It doesn't have the option to sleep or hybernate however.
In preferences you can select the method of shut down which may depend on which desktop environment (KDE, GNOME or Xfce) or display manager (kdm or gdm) are you using. You can also specify the exact command it should initiate before executing the auto shutdown, restart or logout.
For installation type [sudo apt-get install gshutdown] in terminal.
