There are only two "before-battle" speeches of any note. The first is the St. Crispin's Day speech from Henry V (Shakespeare, W.) The other is "Was it over when the Germans bombed Pearl Harbor?" from Animal House (Kenney-Miller-Ramis).

Not so much the entire speech, but the line from Braveheart, "They may take our lives, but they'll never take our freedom" is over-quoted for a reason: it's a killer line.

Al Pacino's "Game of Inches" speech in Any Given Sunday is also quite stirring.

Well, the Patton speech is obviously good...

Now, I want you to remember. . .
. . .that no bastard ever won a war.
. . .by dying for his country.
He won it. . .
. . .by making the other poor dumb
bastard die for his country.

Or Gunny Highway from Heartbreak Ridge...

Highway: My name's Gunnery Sergeant Highway and I've drunk more beer and banged more quiff and pissed more blood and stomped more ass that all of you numbnuts put together.

Highway: Take your post. The Marines are looking for a few good men. Unfortunately you ain't it. We will blaze a path into battle for others to follow. Surrender is not in our creed. Let me here you say that.
Lance Corporal Fragatti, Aponte, Profile, Quinones, Collins, Marine, Corporal 'Stitch' Jones: [mumbling] Surrender is not in our creed.
Highway: Louder or the next time you leave this base for R&R you'll be collecting your pensions.
Lance Corporal Fragatti, Aponte, Profile, Quinones, Collins, Marine: Surrender is not in our creed!
Highway: Louder!

And now... For some pickup lines:

"I appreciate this whole seduction thing you've got going on here, but let me give you a tip: I'm a sure thing."
- Julia Roberts to Richard Gere in Pretty Woman

"You came back to this bar to see me tonight, didn't you?"
"What if it wasn't you I came here to see tonight?"
"Well, ya' got lucky."
- Paul Newman and Charlotte Rampling in The Verdict

"Marry me, and I'll never look at another horse."
- Groucho Marx to Margaret Dumont in A Day at the Races

I suppose I should mention the obligatory "You complete me" of Tom Cruise to Renee Zellweger in Jerry Maguire but it's just SO overused...

I liked Theoden's speech before Pelennor Fields the best of any speech in the LOTR movies. The sword on the pikes thing was pretty cool too. :)

Pre-battle speeches:

-"So no more running. I aim to misbehave."
Captain Malcolm Reynolds, Serenity

http://www.youtube.com/watch?v=G4VLeMNq82o

-"By all that you hold dear on this good Earth, I bid you stand, Men of the West!"
Aragorn, The Return of the King

http://www.youtube.com/watch?v=9GgSdiX0kDI

-"To victory!"
Delios, 300

http://www.youtube.com/watch?v=sFOl-QXpLc4&feature=related

Opening Lines

-"The world has changed. I feel it in the earth, I feel it in the water, I smell it in the air."
The Fellowship of the Ring

http://www.youtube.com/watch?v=xv6hWlPudng

-"If you look for it, I get the sneaky feeling you'll find that love, actually, IS all around."
Love, Actually

http://www.youtube.com/watch?v=RkjyRU3dLXU

-"What was that?"
Serenity

http://www.youtube.com/watch?v=G1IMM5XOwaM

-"When I was young I met this beautiful girl on a lake."
What Dreams May Come

http://www.youtube.com/watch?v=1pHCtLzmras

this is going to sound weird, but my favorite all-time line of dialog (i'll consider it a pre-battle speech) comes from peckinpah's the wild bunch, and it's two words.

"let's go."

the whole story of the wild bunch is that there's this gang of gunmen who betray each other and lie to themselves about their adherence to a supposed code of dignity.

bill holden delivers this line in the lead-up the final bloodbath, and in his performance, really in his eyes, you get the entire film summed up in one line, one shot-- the gang finally lives up to what they are aspiring to be, and it kills them all.

Embarrassed to say this but I almost cried when I watched this summer blockbuster:

President Whitmore (Bill Pullman) Independence Day - I've shortened it.

Good morning. In less than an hour, aircraft from here will join others from around the world.... And should we win the day, the Fourth of July will no longer be known as an American holiday, but as the day 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!