"Do you like our eye?" "It's artificial?"
"Of course it is." "Expensive?" "Kinda."
So I saw a video of a Gakken WorldEye running it's bundled animations of planets rotating, and I thought, this might make a fun xscreensaver output device: it's probably just a matter of tweaking the gluPerspective parameters to de-fish-eye things in the right way. There aren't too many savers that would benefit from a 180° display -- actually maybe only glplanet, discoball, geodesicgears and sonar -- but it's worth investigating.
Then I saw a video of one with a giant eyeball on it, and I thought, "How did I not think of that! It's cool that someone put a pre-recorded MP4 of an eye on that thing, I should do something like that but really overengineer the living shit out of it."
But oh no, this was not necessary. @PaintYourDragon has done some fine work here. It is over-engineered well beyond what I had imagined. Customizable iris and sclera. Editable eyelid profile. Different eyelids for left, right and cyclops eyes. Pupil dilation controlled by a photoreceptor. Button inputs for blinking and winking. It's fantastic.
(I am actually slightly surprised that cat and goat-shaped pupils are not already supported. One must assume that that's coming in the next release.)
Anyway, the first WorldEye I ordered arrived non-functional. The firmware appears to be alive, but the little internal projector won't light up. I tore it apart and it lit up for a minute, but then stopped again, so there's probably some microscopic cracked trace somewhere. The second one worked fine, though.
There seems to be no way to make it default to HDMI input, so if it ever loses power it won't start looking at you without being fiddled with. But, it does provide enough juice on USB to run the Pi, so that's handy.