[Ladyada] and [pt] had an old keyboard from NeXT, but since it used a custom protocol it wasn’t usable with modern hardware. So they built a custom device to convert the NeXT protocol to USB.
They would make a great USB conversion keyboard, but the board to board connector is very hard to find, and no one has yet managed to get the keyboard and track point working as a USB HID device.
The Airwave is a physical stand that looms over your keyboard and includes infrared cameras that track 27 points in each hand ...