Here's the link to the 'afro_nfet.hex' file I've been using for my Afro 12As, should also work for Afro 20As and Afro 30As.

Link

I found it was a bugger to re-flash them via the single wire link as the stock firmware had the silicon chip ID set to an ATMega328 instead of an ATMega8 which is what they actually are. I eventually used the force option on AVRDUDE to just jam the firmware in there with no concerns to warnings. I wouldn't recommend this route, but it did work *shrug*.

#edit# I generated these files using the RapidFlash Google Chrome App.