Also from the gun episode:

"But Marge, I swear....I never thought you'd find out."

and, of course....(read below)

"Lisa honey, just because I don't care doesn't mean I don't understand"

"I am so smart, I am so smart, s-m-r-t....I mean s-m-A-r-t."

"You never know when an old calendar might come in handy! Sure, it's not 1985 right now, but who knows what tomorrow will bring?"

"We'll be rich Marge, rich as astronauts!"

"Marge, it takes two to lie. One to lie and one to listen."

"The only monster here is the gambling monster that has enslaved your mother! I call him Gamblor, and it's time to snatch your mother from his neon claws!"

"Or what? You'll release the dogs, or the bees, or the dogs with bees in their mouth and when they bark they shoot bees at you?"

AND FINALLY THE ONE THIS LIST CAN'T DO WITHOUT
"Yes, honey...Just squeeze your rage up into a bitter little ball and release it at an appropriate time, like that day I hit the referee with the whiskey bottle."

HOMER: Look kids, I just got my party invitations back from the printers.
LISA: Come to Homer's BBBQ, the extra B is for BYOBB.
BART: What's that extra B for?
HOMER: That's a typo.

"I've come to hate my own creation - now I know how God feels."

"Marge, prepare the emergency ham!"

"Margaritas - that's Mexican for 'Marge.'"

After meeting the British Prime Minister:
"We just met Mr. Bean!"

"It's Saint Valentine's Day!! God wants us to do it!"

And, for Padgett, a Marge Simpson quote:

"We can stand here like the French, or we can do something..." Marge Simpson,

Wow! A tribute! Thanks. Here's another similar one. On the old show Cybill, Cybill Shepherd had a job giving out singing telegrams. She came home dressed in a gorilla suit one day after work. Her friend, Mary Ann, said to her, "Either you're dressed as a gorilla or you're a French woman".

Mary Ann had another great line. One morning she woke up on Cybill's couch after a night of partying. She looked around and said, "Thank God. I'm indoors".