Mel likes to smell pretty flowers.  He also finds Moe hideous.

Mel is horrified at the blatant waste of sugar after Homer dumps his illegal cache into the harbor.

Mel praises Snowball II, and parties with a franka (?) snake on the Krusty the Klown Show.

Mel offers advice to Bart and helps the warring factions of Springfield make peace (atta boy, Mel!).

"'Scuse Me While I Miss the Sky" - EABF11 

Once again, Mel is part of an angry mob of townspeople. This time, he's freaked out from sleep deprivation.

Mel patronizes the Leftorium. Is Mel left-handed?

Mel attends Homer's out-of-control housewarming party at the First Church of Springfield. He's also once again a part of angry mob, which blames Homer's taking over of the church when it won't stop  raining.

Mel is in the audience at the Spellympics in Calgary. Once again - is Mel this desperate for entertainment, or does he have a secret child?

Milhouse has a Sideshow Mel poster on his bedroom wall. Yes!

Mel waits in line for a crack at Grandpa Simpson's inheritance.

Mel attends the roasting of Homer and is appalled by Agnes Skinner's choice of evening wear.

Mel eats at Luigi's and toasts the newly large Marge.

Mel trades in his guns in search of world peace, then later sings the praises of gun violence.

The mob truly runs amok in this episode, with Homer becoming the law & Mel agreeing with a hideous crone in yet another town meeting.

"I Am Furious Yellow" - DABF13

Mel spots the newly-famous 'Angry Dad' (Homer) out on the street. Once again part of an out-of-control mob, he aids in rocking Homer's car back & forth.

In the "Homer's Odyssey" segment, Mel is among the suitors who patiently wait to become Marge's suitor, only to be impaled by Homer upon his return; in the "Hamlet" segment, Mel is one of the members of Krusty's acting troupe & gets to pour poison into Krusty's ear!

Quite possibly the first appearence ever by Mel. He plays his signature slidewhistle before 'Itchy & Scratchy'.

"Black Widower"-8F20
Mel anxiously watches Krusty reconcile with Sideshow Bob on Krusty's telethon.

"When You Dish Upon a Star"-5F19
Once again part of an angry mob, Mel storms the Kim Basinger/Alec Baldwin complex holding aloft a sign reading "You complete us".

Bonus!

"She Of Little Faith" - DABF02

Mel really likes the First Church of Springfield.

Mel manages to get a spot in the crowded Flanders' bomb shelter.

Mel plays a fiendish Snidley Whiplash type in a skit on the Klown show.

"Bart's Inner Child"-1F05
Mel attends the Brad Goodman self-help seminar. No reason given as to exactly what Mel's problem is...

Mel sings 'Auld Lange Syne' with Krusty on New Year's Eve.

(You're really going to have to look close to spot Mel in this one.)

Mel has to go to Springfield Memorial Hospital after he gets stuck in a cannon.

Mel refuses to cover for Krusty as he sexually harasses Ms. No-Means-No.

Mel sings the praises of Sanitation Commisioner Homer and of garbage-people in general.

"All Singing, All Dancing"-5F24

A clip of Krusty and Mel singing 'Send In the Clowns', from "Krusty Gets Cancelled", is featured.

"I'm Goin' to Praiseland" - CABF15

Mel goes to Ned's Christian theme park, and doesn't like it one bit.

"Skinner's Sense of Snow" - CABF06

Mel feels it in his bone (the one on his head).

"Homer the Great"-2F09
Mel is a member of the Stonecutters (soon changed to the Ancient Mystic Society of No Homers).

"Homer Vs. Dignity" - CABF04

Mel awaits an attack by seagulls.

"Natural Born Kissers"-5F18
Mel is the first to spot a naked Homer dangling from the rope of a hot air balloon as it flies into a crowded football stadium. 

Mel patronizes Moe's bar/speakeasy both before & after alcohol is outlawed.

A noticeably overweight Mel ambles through what must be the Restaurant District of Springfield.

Mel takes part in the Springfield Marathon.

Mel loves apples!

Mel attends the preview screening of Mel Gibson's new movie. (Coincidence...I think not.)

Mel's itchin'  to accuse someone of witching' in the 'Easy-Bake Coven' segment.

Mel says "our children" aren't safe with Homer. Mel has a child?

Mel relaxes in his spare time at Duff Stadium.

Krusty & Mel watch the lottery drawing together.

"Homie the Clown"-2F12
The first and only appearance of Weeble-Wobble Sideshow Mel.

Mel commiserates with Bart outside the magic shop.

Mel is part of the mob of townspeople aghast at the sexual salaciousness of Principal Skinner and Mrs. Krabappel.

Krusty knocks one of the walls of Mel's dressing room down.

Mel is part of yet another angry mob in the opening 'Munster'-style segment; also can't believe dolphins can talk in last segment.

"The Front"-9F16
Mel is assigned to find spots on Krusty's body on which to attach nicotene patches.

"Marge Vs. The Monorail"-9F10
A quick glimpse of Mel at the town hall meeting, singing about the monorail.

"My Sister, My Sitter"-4F13
Mel is one of the horrified townspeople who, after seeing Lisa dragging an unconscious Bart through the mud,  thinks she is a drug-crazed, homicidal lunatic.

"I Love Lisa"-9F13
A drunken Mel tells Krusty off, on-camera.

"Krusty Gets Kancelled"-9F19

After the Krusty show is cancelled, Mel finds a job at the Gulp 'n' Blow. Krusty begs him to come back and help him, but Mel refuses, saying his new boss treats him with more dignity.  Eventually, Mel relents, and sings "Send in the Clowns" with Krusty on his Komeback special.

"Bart Gets Famous"-1F11
In his new job as Krusty's assistant, Bart serves Mel a sandwich with cheese on it.  Mel, being lactose intolerant, gets violently ill and verbally abuses Bart from the bathroom.

Mel makes sport of the lack of tennis talent in the Simspon gene pool.

"Secrets of a Successful Marriage"-1F20
Mel is a student in Homer's marriage class. After being invited to the Simpson house during dinner to observe a marriage in action. Mel finds the odor of their food disturbing.

"Colonel Homer"-8F19
Krusty is backhanding Mel and screaming at him to stay away from his sister when Lurleen Lumpkin's voice blares from the radio. After hearing her song, Krusty mellows and gives Mel money to take her to the Copa.

"The Cartridge Family"-5F01
Mel inadvertently starts the soccer riot when he gets bored and tries to leave. Also appears to be a member of the NRA (Mel, no!).

"Realty Bites"-5F06
Marge almost sells Mel and Barbara a home with a large bowling alley, until Mel realizes he doesn't much care for bowling.

"Who Shot Mr. Burns?"
Pts. 1 & 2-2F16 & 2F20

A tour-de-force for Mel. At a town meeting, Mel threatens Mr. Burns and brandishes a switchblade. Later, Mel figures out how Smithers could not have shot Burns, and clears his name. Revealed for the first time: Mel smokes a pipe.

"Radio Bart"-8F11

Bart tunes in to the Krusty show to see the birthday announcements. Mel brings out a giant birthday cake. Krusty trips him. Mel lands on his face, but the cake stays together. As Mel gets up, Krusty kicks him in the butt, sending him head-first into the cake. Mel's hair catches fire on the candles. Mel also sings on 'Sending Our Love Down the Well.'

"Lisa the Skeptic"-5f05
A veteran of many town mobs, Mel shouts "I'd like to hear from Lionel Hutz," as the townspeople debate who owns the angel bones discovered by Lisa.

Krusty hits Mel in the head with an axe. Mel has to be held up by Corporal punishment for the show's closing song.

"Brush With Greatness" - 7F18

Sideshow Mel plays the slide whistle while the show does a remote from Mount Splashmore.

"Bart the Fink"-7503
Mel delivers the eulogy and unveils the Krusty the Clown Memorial at Krusty's funeral. 

"I'm with Cupid"-AABF11
After Apu makes them all look bad by lavishing Manjula with gifts, Mel sits at Moe's with Homer and Skinner, bemoaning his recent lack of oral gratification.

"Sunday, Cruddy Sunday"-AABF08
Mel catches a pass from Dan Marino when he goes to the Superbowl with Wally Kogen, Homer, Krusty, etc.

"22 Short Films about Springfield"-3F18
Mel, along with everyone else, offers Lisa advice on how to get gum out of her hair.

"Treehouse of Horror III"-9F04
Zombie Mel jumps out of a box and eats Krusty's brain, turning him into a zombie. 

"Seperate Vocations"-8F15
While out on a night ride-along with Lou and Eddie, Bart spies Mel simultaneously walking his dog and roller-skating.

"Brother's Little Helper"-AABF22 While doing a sketch for the show, Sideshow Mel is dressed in an evening gown and billed as Sideshow Melanie. Later, Mel is in the cowering group Bart points his tank toward.

Bonus!

"Lady Bouvier's Lover"-1F21
Krusty forces Mel to lead a band of monkeys playing a Strauss waltz on kazoos, but one of the monkeys stops.  Mel's baton-poking prompts the monkey to lunge for his throat.  Soon, the other monkeys join in.

"You Only Move Twice"-3F23
Mel bids the Simpsons farewell as they move to Cypress Creek.

"The Two Mrs. Nahasapeemapetilons" - 5F04

Mel gets a garland at Apu's wedding.

"Faith Off"-BABF06

Mel marvels at Bart's supernatural healing ability. He takes Krusty to Bart to be healed of his vocal chord paralysis, gained when Krusty tried to cram too many 'K's into a comedy sentence.

"The Mansion Family"-BABF08

After Homer is enlisted to caretake Mr. Burns' estate, he takes everyone on a cruise to lawless international waters to party. Mel amuses himself by cheering two monkeys in a knife fight and boogieing to "China Grove".

"Joy of Sect"-5F23

Mel joins the Movementarians, and is covered in dust by The Leader as a sign of favor.

"The Bart Wants What It Wants" - DABF06

Mel checks out the basketball game.

"Alone Again, Natura-Diddly"-BABF10
The infamous episode in which Maude Flanders dies!  Mel is one of the more conspicuous people at her funeral.

"Bart After Dark"-4F06
Mel plays the slide whistle during "The Spring in Springfield'.

Mel has the bottom left on 'Springfeild Squares"

"In Marge We Trust"-4F18

Mel needs Marge's help the most when she's the church Listen Lady.

"The Last Temptation of Krust"-5F10

 In the Pimento Grove, Krusty sits in a booth with Sideshow Mel and reads the review of his act at the comedy festival.    

"Bart Star"-5F03
At the Free Health Fair, Mel sits on the couch at the Are You Crazy? booth.

Mel is one of the pasty-faced goons in the mutant horde which chases down Homer.

"Miracle on Evergreen Terrace"-5F07

Mel is one of the townspeople who gives to the Simpsons when Bart, after burning up the Christmas tree and all the gifts, tells everyone a burglar stole them.

Mel is one of the crowd calling for the end of the kids' transmission of adult secrets over the radio. (Wonder what he was scared of being revealed...?)

Mel is in the audience for the Springfield Elementary talent show.

Mel is amazed at Ned Flanders' lifelong resistence to all major urges.

Mel lives in Old Springfield, the rich side of town.

Mel attends the big announcement about Lisa Land. He is horrified at Jesse cutting the wires to the Lisa log.