The F-Stop Watch from Neatoshop lets you tell the relative aperture time of a 50mm lens. Not quite but it does do real time with aperture settings instead of traditional numbered settings on the dial face.
Price for the neat watch is around $36.
A great photography-inspired watch! Dial tells time with relative aperture (F-Stop)
Quartz movement with batteries included
Leather strap with metal clasps
Fits most adult wrists
Comes in a collectible tin