Thanks for posting that - its a good summary of the options available.
I think a backup can also be made to another, remote machine (especially if you arent backing up a huge amount.) For instance, the IT service here back up all our files on the super computer every 24hrs - I just copy work on my personal machine to my storage on that machine and then all the hard work is done for me
In addition some institutions use tape drives : advantage is that they store a huge amount, disadvantage is that its a real effort to navigate to the correct location on them.
I think many people also forget to store their backed up files away from the computer, so that fire or the such doesn't destroy everything.
P.s. nice to see the floppy disk in there