Some five years ago or so Thinkpads had an ulltrabay adaptor that was a device carrier. You pop off the cdrom drive and stick the carrier in its place.
They made adapters that would let you place a palm pda in the carrier or a numpad. You press a button and the drawer opens with the numpad (or pda.)
It's convenient to carry this stuff inside your laptop, I for one, haven't had any use for a built-in cdrom drive in about a decade or thereabouts. ( And yes, I do have a bluetooth MoGo mouse that goes inside the pcmcia slot.)