That's not really what I meant; the device you linked is an example of the second kind of thing, a "floppy disk emulator."
A floppy version of a "cassette adapter" would be a floppy disk on one end, and a USB cable on the other. You'd feed the adapter disk into a floppy drive; the cable would dangle out of the front of the drive; and then you'd plug the cable into a USB mass-storage device.
As with an audio cassette adapter, this would be a way to feed data into a device through the magnetic read head — making the drive believe for analogue RF reasons that there's a flux-recorded medium in there; one that reads off as whatever data you're playing down the line.
