The Reference Desk/Clockwork is open. Please wind it up

From Tardis Wiki, the free Doctor Who reference

Performing a rehaul of Clockwork Droids, Clockwork robots and the like, the Clockwork page has become free of the robots, which were restricting the content of the page.

Consequently, I have a request to all of you. If you can remember some cool important piece of clockwork technology in the DWU, please, add it to the page. The Great Clock and the Doomsday Chronometer are already there, as well as Big Ben, but there must be more. Also I remember the Doctor always admiring a good piece of clockwork, but can't remember exact stories. A little help?