Usually when the Muppets make guest appearances on variety and talk shows, they usually only appear for one sketch or interview. This is for guest appearances where the Muppets appear throughout.
The Muppets were heavily featured on the show during the week of July 19-22, 1966.
An entire show in 1971 focused on Jim Henson and the Muppets.
Kermit the Frog guest-hosted on April 2, 1979.
Kermit hosted on April 1, 1994.
An episode in 2004 was declared "Muppet Day".
An entire hour of one episode in 2008 was taken over by the Muppets, in what was called "The Muppets Take Over Today".
Long-running comedy festival Just for Laughs dedicates a special hosted by the Muppets.