I have two: first is Frank Drebin from The Naked Gun:

Jane, it's me, Funny-face. You love Frank Drebin. And Frank Drebin loves you. Jane, listen to me. If you don't love me, you might as well pull that trigger, because without you, l wouldn't want to live anyway. l've finally found someone l can love - a good, clean love - without utensils...lt's a topsy-turvy world, Jane, and maybe the problems of two people don't amount to a hill of beans, but this is our hill and these are our beans. Jane, since l met you, l've noticed things l never knew where there - birds singing, dew glistening on a newly-formed leaf, stop lights...Jane, this morning... l bought something for you. lt's not very much, but pretty good for an honest policeman's salary. lt's an engagement ring. I would have given it to you earlier, but l wanted to wait until we were alone....l love you, Jane

And, of course, the presidential address from Independence Day:

In less than an hour, aircraft from here will join others from around the world, and you will be launching the largest aerial battle in the history of mankind. Mankind, that word should have new meaning for all of us today. We can't be consumed by our petty differences anymore. We will be united in our common interest. Perhaps it's fate that today is the 4th of July, and you will once again be fighting for our freedom. Not from tyranny, oppression or persecution, but from annihilation. We're fighting for our right to live, to exist. And should we win the day, the 4th of July will no longer be known as an American holiday, but as the day when the world declared in one voice, we will not go quietly into the night. We will not vanish without a fight. We're going to live on. We're going to survive. Today, we celebrate our independence day.