Moe: “You know what I blame this on the downfall of? Society!”
Burns: If you can take advantage of a situation in some way, it’s your duty as an American to do it. Why should the race always be to the swift or the jumble to the quick-witted? Should they be allowed to win merely because of the gifts God gave them? Well, I say cheating is the gift man gives himself!
Homer: Mr. Burns, I insist that we cheat.
Burns: Excellent.
After Homer and Marge are trapped (naked) in the mini golf windmill and escape by tipping it over, Ned notices a shoe and necklace left behind and exclaims “It’s people! People soiled our green!”
Followed by Peter Frampton complaining later in the episode “Cypress Hill stole my orchestra”.
Lisa :" Neruda said, 'laughter is the language of the soul."
Bart: “I’m familiar with the works of Pablo Neruda.”
Sure you are, Bart. That cracks me up everytime.
Salesman: Whoa, whoa, a fat, sarcastic Star trek fan! You must be a devil with the ladies.
Comic Book Guy: Hey, I, uh, de-oh…
Salesman: Gee, I hate to let you down, Casanova, but no receipt, no return.
Comic Book Guy: Huuuh. Very Well. I must hurry back to my Comic Book Store where I dispense the insults rather than absorb them.
Homer: Got any messages for Jimi Hendrix?
Vet: Yes, pick up your puppy!
(Pan over to a depressed looking dog wearing a tie-dyed bandana.)
In the Lemon Tree episode Bart and his gang take slow solemm steps over the Shelbyville-Springville border as Lisa and Janny run back and forth with a kite.
“Theres a lemon behind that lemon shaped rock!”
And that last part is, itself, a take-off on a similar scene in Blazing Saddles! A two-for-the-price-of-one zing!!
Never forget Leonard Nimoy’s first appearance, in the Monorail episode.
“A solar eclipse. And so the cosmic dance continues.”
Guy next to him: Does anybody want to trade seats?
Later…
Nimoy: Well, my work here is done.
Bystander: But you didn’t do anything.
Nimoy: Didn’t I? And he disappears in a transporter effect.
:::ahem::: High Anxiety
No, I think Ponder is referring to the Count Basie orchestra in Blazing Saddles.
In the episode where the Simpsons get cable and Bart and Homer going on a tv watching binge, despite the fact that Bart has an achievement test at school the next day. Bart sits down to take his test and starts hallucinating from lack of sleep. He imagines that a group of characters from tv are holding him above their heads while dancing in a circle. One of the characters holding him above their heads is Bender, a character from Futurama (Groening’s other animated show).
I think the funniest part of that scene is the fact that Homer is gorging himself on ice cream while driving the ice cream truck.
Alien: Uh… I bring you love!
Lenny: It’s bringing love! Don’t let it get away!
Carl: Break its legs!
I especially like the way he says “Ooh, that’s raspberry” as he’s driving the truck.
“dont chase me… Im full of chocolate.” Cracks me up.
Only got through page 4 of the thread so I hope it’s not a repeat:
In the Biblical stories episode, when Wiggum shoves Lisa and Milhouse into the pyramid: “Give my regards to the British Museum!”
In the episode (‘monorail’?) where the town has to decide between Marge’s idea to fix up Springfield’s roads or get the “Monorail!”: I like the scene featuring a birds eye view of the town’s roads with chasms in them and then you see the Popcorn van fall in-
Driver: “Whoa!..”
Also hilarious, the episode where the Simpsons go to Tokyo and take part in the “Super Fun Happy Family Make Wish Game!” which parodies the often life threatening Japanese game shows.
Sorry if any of this has been said.
I don’t think any of these are repeats, but if they are, hell, we’ve probably all forgotten them and are ready to laugh at them again. 
From last night’s syndicated episode.
Apu is onthe phone with his mother trying to get out of his arranged marriage. Homer talked him into lying about already being married. His mom asks Apu why he didn’t tell her about it. Apu looks worried and is fumbling for an answer. He looks to Homer. Homer gets out paper and pencil to write something down. He holds up the paper to Apu and it says “Where are
the sticky buns?”
Burlesque house owner: Mr. Simpson, why are you wearing a grocery bag?
Homer, in a very dignified manner: I have misplaced my pants.
Burlesque house owner: Mr. Simpson, why are you wearing a grocery bag?
Homer, in a very dignified manner: I have misplaced my pants.