Well, some of my favorites (Jaws "get another boat" and Apocalypse Now "napalm") already mentioned. Here are two others, although they are more monologues than quotes:
"But love don't make things nice, it ruins everything! It breaks your heart, it makes things a mess. We, we aren't here to make things perfect. Snowflakes are perfect, stars are perfect. Not us! Not US! We are here to ruin ourselves and, and to break our hearts and love the wrong people and, and die! I mean that the storybooks are bullshit. Now I want you to come upstairs with me and, and get in my bed!!"
Moonstruck (1987). Ronny (Nicholas Cage) to Loretta (Cher). Best seduction speech ever.
"I have… seen things you people wouldn't believe… Attack ships on fire off the shoulder of Orion. I watched c-beams glitter in the dark near the Tannhäuser Gate. All those… moments… will be lost in time, like tears… in... rain. Time… to die…"
Blade Runner (1982). Replicant Roy Batty's (Rutger Hauer) dying words. One of the most beautiful soliloquies in science fiction film... or any kind of film.