No, for a possible future project I thought about taking a PDA keyboard, hacking it and building a small joystick control panel out of the pieces from one of these other joysticks. Then, you can play MAME on a PDA with a joystick/controller.
It may just be easier to get a USB joystick and a USB adapter for an iPaq and do something that way.
But, all options are worth thinking about for creativity's sake.