Force umount the unresponsive drive

Pic of DVD on way to driveThe newbie states that when he pushes the Eject button on the DVD drive of a server running a certain Redmond-based operating system, it will eject immediately. He then complains that, in most enterprise Linux servers, if a process is running in that directory, then the ejection won't happen. For too long as a Linux administrator, I would reboot the machine and get my disk on the bounce if I couldn't figure out what was running and why it wouldn't release the DVD drive. But this is ineffective.
Here's how you find the process that holds your DVD drive and eject it to your heart's content: First, simulate it. Stick a disk in your DVD drive, open up a terminal, and mount the DVD drive:
# mount /media/cdrom
# cd /media/cdrom
# while [ 1 ]; do echo "All your drives are belong to us!"; sleep 30; done

Now open up a second terminal and try to eject the DVD drive:
# eject
You'll get a message like:
umount: /media/cdrom: device is busy
Before you free it, let's find out who is using it.
# fuser /media/cdrom
You see the process was running and, indeed, it is our fault we can not eject the disk.
Now, if you are root, you can exercise your godlike powers and kill processes:
# fuser -k /media/cdrom
Boom! Just like that, freedom. Now solemnly unmount the drive:
# eject
fuser is good.