...there was the Gemini Special Edition clamshell iBook.This graphite iBook conversion by Assistive Technologies may be the first ever tablet Mac. Long before the advent of Axiotron Modbook. Gemini is known as an Augmentive and Alternative Communication (AAC) device. It originally sold for US$6,914.
The owner bought it as a parts machine to salvage some regular clamshells, but couldn't bear to "part it out." He thinks that it may have been an officially Apple-authorized device created primarily for disabled people, featuring added ports for a wheelchair joystick, switch and top-mounted USB. The Gemini also includes a second speaker – the standard clamshell iBook had only one.
It's for sale on eBay.