I have over a dozen mechanical watches and what goes on inside them is a big reason why I wear them. I really appreciate the craftsmanship and intricacy of the tiniest little springs and sprockets all working together.
This guy's site is just amazing in general. He has these interactive articles on tons of subjects, like GPS, bezier curves, boat propellers, cameras, etc etc. I'm learning too much right now (I mean, I already had a general idea about most of it, but he makes you actually understand shit).