Most any line from Steel Magnolias is good. There are also some great one-liners from Under the Tuscan Sun.

Anchorman may be the most quotable movie in film history.

Fargo is up there as well.

I find myself quoting "Spaceballs", "Pulp Fiction" and "Quest for The Holy Grail" a hell of a lot.

Well, those and whatever the conversation triggers in my head.

Some of the ones already mentioned I quote, here are some more:

"St. Elmo's Fire" "Rivers Edge" "Jackie Brown" "The Devils' Rejects" "Goodfellas" "Casino" "Jaws" All of Kevin Smiths movies "Do The Right Thing" "Mo' Better Bues" "Jungle Fever" "Boogie Nights" "Talledega Nights" "Animal House" All the "Vacation" movies

Is that enough?

I can't stop finding ways to incorporate "That's What She/He Said" into every conversation I have....not that it originally came from a movie.. but on the subject of quotes. Mmmmmm. The Office.

My wife and I do that ALL THE TIME. With some of my friends at work too.

Any or all of the last three Star Wars, Office Space, Anchorman, The Godfather Parts 1 and 2, The Philadelphia Story (if you haven't seen it, you won't understand why), almost everything Spicoli said in Fast Times at Ridgemont High, All About Eve, Sunset Blvd, In The Heat of the Night ("They call me Mr. Tibbs!"), Unbreakable, Dog Day Afternoon, The Hunchback of Notre Dame, Carrie, Kindergarten Cop, The Wizard of Oz, Frankenstein, Blazing Saddles, Young Frankenstein … I could go on.

Oh, and Austin Powers: International Man of Mystery.