I remember a thread back during my GH time, where appearances of mechanical/collectible keyboards.
One of the more memorable appearances was a Model M featured in many Stargate episodes.
On rewatching some episodes of Doctor Who I discovered one of the rarer keyboards: a G80-9009, known in the Reuters branding (admittedly a keyboard I would love to own, if I had the money). Apparently the BBC had some of these lying around as props, as they appeared in the episode "Rise of the Cybermen".