Genesis has been doing medleys of some songs in one form or another since 1976. Here are some of the better ones available on Youtube.

1977
“The Lamb Lies Down on Broadway”
” – The Musical Box (Closing section)”

1978
“Dance on a Volcano”
– Drum Duet
– “Los Endos”

1982
“In the Cage”
– “The Cinema Show”
– “Riding the Scree (Teaser)”
– “The Cinema Show (Reprise)”
– “The Colony of Slippermen (c) Raven”
– “Afterglow”

1983
Old Medley:
“Eleventh Earl of Mar”
– “Squonk”
– “Firth of Fifth”

(1983–1984)
“In the Cage”
– “The Cinema Show”
– “…In That Quiet Earth”
– “The Colony of Slippermen (c) Raven”
– “Afterglow”

1986
“In the Cage”
– “…In That Quiet Earth”
– “Apocalypse in 9/8 (Co-Starring the Delicious Talents of Gabble Ratchet)”
– “As Sure As Eggs Is Eggs (Aching Men’s Feet)”

1988
“Turn It On Again”
– “Land of Confusion”
– “Misunderstanding”
– “Throwing It All Away”
– “You Can’t Hurry Love”
– “Shortcut to Somewhere”
– “All I Need Is a Miracle”
– “That’s All”
– “Tonight, Tonight, Tonight”
– “Invisible Touch”
– “Turn It On Again (Reprise)”

1992
Old Medley:
“Dance on a Volcano”
– “The Lamb Lies Down on Broadway”
– “The Musical Box”
– “Firth of Fifth”
– “I Know What I Like (In Your Wardrobe)”
– “That’s All (Teaser)”
– “Illegal Alien (Teaser)”
– “Misunderstanding (Teaser)”
– “Follow You Follow Me (Teaser)”
– “Stagnation (teaser)”
– “I Know What I Like (In Your Wardrobe) (Reprise)”

2007
“In the Cage”
– “The Cinema Show
– “Duke’s Travels”
– “Afterglow”

Check out the wiki page for a list of all Genesis Medleys