There aren't many accessories for the system that does everything, and even plays video games on top of all that, but here are the ones I've managed to acquire.

Borrowing more than a little in design from Sega, and possibly InterAct, the Goldstar 3DO Control Pad is rock solid. It includes a headphone jack and volume control dial, and has a controller connector on it, to allow daisy-chaining with the risk of having someone yank your controller while you're playing multiplayer games, but you can turn the tables on them by unplugging their controller entirely. But either action is dirty pool, and is without honor. There is one important point of failure, in that the direction pad is locked in place by tiny plastic tabs, which can break off quite easily, leaving the d-pad to spin in place. My fix for this was to cut notches into the collar for the d-pad disc, and matching notches in the d-pad ring, then epoxy scrap plastic strips in these notches to lock the ring in place. We can thank Nintendo's patents for this particular mess.

Effectively a no-frills, low-cost controller, the Logitech 3DO Control Pad is still plenty capable, and features a Y connector for daisy-chaining more controllers. The shape is a bit lacking, but isn't uncomfortable. Not a bad pad, overall.

For those favoring the SNES pad, the InterAct ProPad brings the familiar diamond face button layout, with shoulder buttons and edjustable turbo fire. The X button duplicates the STOP button, which cannot be re-mapped in most games, so you may find yourself pausing when attempting to perform a light kick in Super Street Fighter II Turbo.

While it lacks a headphone jack, the ProPad has a Y connector to allow daisy-chaining of controllers at the system end instead of at the controller, which should prevent your dog from yanking your controller out of your hands.