Here’s a page from MuppetWikipedia (there’s a MuppetWikipedia?) talking about Muppet eyes.
I learned some fun Muppet-eye facts:
Early Muppet eyes were made of ping-pong balls.
Most Muppets are deliberately designed to be slightly cross-eyed, which gives the puppet a point of focus and makes it more expressive.
Optimistic characters like Ernie and Rolf look slightly upwards. Grouchy characters like Waldorf look slightly downwards.
The more aggressive or ornery Muppets tend to have eyebrows; the gentler Muppets usually do not.
Pupil size indicates age: young characters have larger pupils than old characters.
And there’s lots more info here.
Some more fun Muppet stuff:
Here are pics of Muppets who “grew” eyelids for sleeping scenes.
Also! Originally, Kermit was not a frog– he was an “abstract lizard-like creature” made of Jim Henson’s mother’s old coat.
The original Cookie Monster had scary teeth.
The first version of Mr. Snuffleuppagus seemed to have an eye infection and is basically the stuff of my nightmares, GAH.
There is a sexy pig Pamela Anderson Muppet named Spamela Hamderson (AMAZING).
The site’s not easy to navigate- none of the entries are tagged very well- but if you wanna wander around in Muppet land for a bit you can try hitting the “Random Muppet Character” link on the left hand side.
PS- Hey, wanna be a Muppet for Hallowe’en? NOOOOOOOOOOOOOOOO