Well, there's also...
Gonzo!
Can't believe nobody mentioned him.
But yeah, there's also Sweetums, and Digit. I think that's the extent of the Muppets I can name. If anyone's seen the Vincent Price episode of the Muppet Show, there's a skit on there where a large monster eats a small orange monster to the tune of "I've Got You Under My Skin" and that little scared orange monster was on the Cosby Show episode.
I think some of them might have been created just for that episode, like say the Doctor who reminded Cliff of taking the Hippocritic Oath
But there's a bunch of familiar faces in there, and it's more of the scarier and monster ones.
I recognize a lot of them, but I'm not sure of their actual names. Sorry I can't be of more help. But anyway, I have the episode on tape and it's definitely worth getting. Gonzo talks about Cliff delivering a Koozbanian baby.