Weekend project, while not quite as done as I wanted it to be, was still a success!
Made a USB reference implementation using the USBTiny firmware only USB 1.1 Low-Speed driver. Haven't actually gotten to do much with it outside of putting the board together and running a couple of python (which I'm learning to love quickly) test scripts. Still, it's nice to have some sort of USB connection without having to go through FDTI, though I suppose I could always do something zany like move to a decent, higher speed 32-bit platform too. But for now, this works.