[cliveh]

There could also be a gear train which, when you line a pointer up to the needle, turns the exposure calculator to show the setting.

I imagine some kind of Steampunk-looking gizmo with lots of brass gears and stuff. Sort of like an Argus C3 on steroids.

Maybe something like this:
http://lh3.ggpht.com/abramsv/SAbnnw2...steampunk6.jpg

That sounds like what I'm looking for.