There I was, just happily googling the Nikon F mount for a story to celebrate the lens mount’s 50th anniversary, and I stumbled on this:
Glico Nikon F Miniature and MACRO Nikkor 35mm F4.5

Unbelievably cute! From what I can make out, these are tiny gifts given away with certain Japanese sweets called Glico. These are from 2002, so unfortunately I don’t think they’re still available. Rubbish.
But the best bit about this whole website has to be the broken English in which it’s written. It’s like poetry:
from the article on the small Nikon F pictured above:
“However, there is only one weak point in it.
It is a camera which cannot be actually taken picture.
Because, the minimum size film which can be loaded into this Glico Nikon F camera is not sold.”
and another beauty, from the World Minimum Nikon White Filter page:
If you mount this small filter on your camera, you can understand ant’s heart.
I recommend this small filter to the all digital poet and an astroboy.
This is actually the first thing that I’ve discovered for myself on the Internet (y’know, without having SwissMiss or Neatorama help me out) and I’m very proud of myself.