Shutdown Sound:
This works on my Xubuntu Natty install. I found a .ogg sound file that I wanted to use as a shutdown sound so needed an command line ogg player to play it.
$ sudo apt-get install ogg123
now add a script as follow script to /etc/init.d as follows
In a Terminal, create the file with, [change mousepad to your favourite text editor]
$ sudo mousepad /etc/init.d/K99shutdownsound.sh
copy the following into the script
#!/bin/sh
#### play sound at startup ####
## reduce volume ##
amixer -c 0 sset Master,0 50%
## play sound ##
/usr/bin/ogg123 /path_to my/shutdown.ogg
save the script and make it executable.
$ sudo chmod +x /etc/init.d/K99shutdownsound.sh
now add a shortcut to /etc/rc0.d where shutdown scripts go and to /etc/rc6.d where reboot scripts go
$ sudo ln -s /etc/init.d/K99shutdownsound.sh /etc/rc0.d/K99shutdownsound.sh
$ sudo ln -s /etc/init.d/K99shutdownsound.sh /etc/rc6.d/K99shutdownsound.sh
Now I get a reboot and shutdown sound.