There was an experiment floating around since 1999 to take a hard disk image file used by emulators and stream it over a serial port to a real apple II(GS) computer. That sat around for over a decade when someone started asking about it, the author of ADTpro (apple disk transfer, take floppy image, copy it over serial to 5.25 inch floppy) noticed, patched it up to work with any apple II/III computer and started to include it with the standard ADT pro files.
Once it was working I decided I was going to port it to a stand alone device, along with ADT itself. havent made it far with ADT but the virtual serial drive is working with an arduino giving my 1986 apple //c a hard disk with a 115,200 baud interface (much faster than a floppy, not quite as fast as something that plugs into the apple's bus, but the //c does not have any slots so I cant use them anyway.)
I am making a limited run of devices, all SMD in a nice case, but before I go though that I wanted to check my schematic against a real device, a "sanity check". This sanity check is made on some radio shack perfboard and performs flawlessly (though I have some HF noise coming from the regulators I would like to clean up first)http://osgeld.a2hq.com/2013/02/02/vshpsh-demo-video/