If you have just the slightliest soldering experience it's easy to make the pad into a 3 button Amiga pad... for more advanced works one could make the start button act as autofire. I use a small tool called Analyzer to help me with the pinouts and testing the modded joys. :-)
I was concidering making a mouse and joy out of a PS controller but haven't gotten one. But I do have 2 N64 controllers now so I'll give it a go soon.