Pretty much every quote the Gravemind has said, but some notable ones;

"This is not your grave, but you are welcome in it." - Halo 2
"Now the gate has been unlatched, headstones pushed aside; corpses shift and offer room, a fate you must abide!" - Halo 3
"Child of my enemy, why have you come? I offer no forgiveness, a father's sins, passed to his son." - Halo 3
"Resignation is my virtue; like water I ebb, and flow. Defeat is simply the addition of time to a sentence I never deserved... but you imposed." - Halo 3

Also, Cortana had some too, but I'll only say up to Halo 3/Reach because I didn't go to Halo 4 yet.

"Don't make a girl a promise ... if you know you can't keep it." - Halo 2
"It asked, and I answered. For a moment of safety, I loosed damnation on the stars." - Halo 3


Other quotes include Rabbit from Twister, who says "He's a corporate kissbutt, man!", Dusty's lines, and the infamous "I've go to go - we've got cows!".

Also, Sonic's infamous line of "No copyright law in the universe is going to stop me!". Good one Sega XD