Here's a few from JHH:
BRUNO--Anthony and Fern's pet: a gigantic Muppet tarantula.
THE SCREAMING NO-NO'S--tiny Muppet humans who scream "no, no!" when they're eaten by Anthony (as a snack).
THE GARBAGE BAGS--they're already listed, but they also appear in TAOEIG.
BARBARA STREISANDWICH--appears in a commercial for a food-related album. She's basically a Muppet sandwich.
SAM AND ELLA--appear in the same commercial to sing "Veal Meat Again". Sam is a greyish-tan Whatnot with a long nose that sticks out. He wears a tux, and has short brown hair and sleepy eyes. Ella is a turquoise Whatnot with curly brown hair, a pink nose, sleepy eyes, thick-rimmed pointy glasses, and a blue dress.
THE DAVE CARP FIVE--a quintet of five fish who sing "Hey Food (not the SS version)" and "Like a Sturgeon" in the commercial.
On drums is a blue-eyelidded Gill Brother in a dark navy outfit;
on sax is the Mother fish with a pirate captain's hat;
on vocals is a "yellow fish"-headed character in a black suit;
on guitar is the Orange Fish (with angry blue eyelids) in a blue Captain's suit with a tri-cornered hat;
and on bass is the Grouper puppet wearing a sailor suit.
And here's a couple from "The Cosby Show: Cliff's Nightmare":
THE HYPOCRITIC OAF--the same puppet used for "The King of the Kingless Land" story from JHH, but dressed as a barber (I don't know why)
THE DISAGREEABLE SAUSAGE SANDWICH--a sub-sandwich filled with lots of onions, sauce, and other stuff.
Both of them also appear on JHH.
I'll send more as soon as possible, but ponder this; in one episode ("The Secrets of the Muppets"), Ambrosius (from "Labyrinth") appears among Muppet dogs (including three from "Dog City", Rowlf, the Storyteller's Dog, and the TOTBP Dog).