You will get an icon on your panel and when you click on it, the cdrom gets unmounted and ejected.

Create a new file:

gksudo gedit /usr/local/bin/eject_cd

Paste the following lines:

#
# Try to unmount a CD-Rom device, then eject it.
#

DEVICE="$1"
ZENITY_BIN="/usr/bin/zenity"


#Ctrl-C trapping
trap ctrlc INT
ctrlc()
{
echo -e "\nAborted by user."
rm -rf $TMP_DIR
exit 2
}


#Show a dialog with zenity
#@param  string  The text to display
show_dialog()
{
if [ "$use_zenity" -gt "0" ] ; then
zenity --error --title "CD-Rom eject" --info-text "$1"
fi
}


#Get parameters
if [ "$1" == "-h" ] || [ "$1" == "--help" ] ; then
echo "Usage: eject_cdrom [-q] DEVICE"
echo -e "Try to unmount DEVICE then eject it if successful.\n"
echo "Possible parameters:"
echo -e "-h, --help\tdisplay this help and exit."
echo -e "-z, --zenity\tuse zenity to displays errors in dialog windows."
exit 0
fi

if [ "$1" == "-z" ] || [ "$1" == "--zenity" ] ; then
if [ ! -x "$ZENITY_BIN" ] ; then
echo "You must install zenity before that."
exit 1
fi
use_zenity="1"

device="$2"
else
use_zenity="0"
device="$1"
fi


#Device check
#TODO: Check if DEVICE is truly a device.
if [ ! -e "$device" ] ; then
echo "Parameter DEVICE is not a file."
exit 1
fi


echo "Trying to eject CD-Rom..."

#Unmount
umount "$device" 2>/dev/null
last_err="$?"

if [ "$last_err" -eq "1" ] ; then
msg="Cannot unmount device $device (busy)."
echo "$msg"
show_dialog "$msg"
exit 1
fi

#Eject
eject "$device"
last_err="$?"

if [ "$last_err" -ne "0" ] ; then
msg="Cannot eject device."
echo "$msg"
show_dialog "$msg"
exit 1
fi

exit 0

Make the script executable:

sudo chmod +x /usr/local/bin/eject_cd

Create a new launcher on a panel (or wherever you want):

Right-click on the panel
'Add to Panel'
'Custom Application Launcher'

Type this (replace /dev/cdrom with your CD-Rom device):

Name: Eject CD-Rom
Comment: Unmount and eject the CD-Rom /dev/cdrom
Command: /usr/local/bin/eject_cd -z /dev/cdrom
Icon: /usr/share/icons/gnome/24x24/devices/gnome-dev-removable.png

Click 'Close'

Note: This script uses zenity to display errors. However if you don't want this feature, remove the '-z' parameter.

To install zenity:

sudo apt-get install zenity

Credits: Sam

A Chinese translation of this article.