Dan Bowman sent me a link to instructions on setting up FDD RAID on OS X. That's FDD, not HDD. Floppies.
This most definitely falls into the because-you-can category, if not the for-when-you're-really-bored category. But it looks like somebody's finally found a way to make floppies reasonably fast and reliable. So now who's going to try it with Zips?