There's so many! Here's a few of my faves:
"Frankly my dear, I don't give a damn." - Rhett Butler (Clark Gable), Gone with the Wind
"Oh, I'm sorry - did I break your concentration?" Jules (Samuel L Jackson), Pulp Fiction
"A wedding? I love weddings! Drinks all around!" Jack Sparrow (Johnny Depp), Pirates of the Caribbean: Curse of the Black Pearl
"Why do they call him the Bullet-Dodger?" Avi (Dennis Farina) "'Cause he dodges bullets, Avi." Bullet Tooth Tony (Vinnie Jones), Snatch
"That reminds me, Marty. You better not hook up to the amplifier. There's a slight possibility of overload." Dr Emmett Brown (Christopher Lloyd), Back to the Future
That's all I can remember at the moment!