I would love to see support added for a USB keypad as a pendant/remote controller. USB Keypads are dirt cheap and available everywhere. Ideally there would be a way to move each axis in each direction, plus a Home key, a pause key, etc.
It would be a simple matter to print laminated stickers to apply over the top of the keys and allow users to operate their X-Carve without having to stand right next to the computer/laptop.
Plus, it's probably easier to support that than it would be to try and add support for a "real" pendant controller.