GOTEK Floppy Emulator Simulator
I've been using the GOTEK USB Floppy Emulator Simulator since the beginning of 2013 and they have never let me down. I haven't encountered a single glitch, bug or issue and can highly recommend them. You can purchase them for around A$ 25 on eBay. The software that came with my units was disappointing and I recommend using this software here from German company ipcas.
The sheet I use to write down the contents of each floppy can be downloaded and printed below.