Charlie Chaplin - The Great Dictator (1940)
This is not really what you might expect out of Charlie Chaplin, but it's still powerful and apt 70 years later.
Kenneth Branagh - Henry V (1989)
It kind of feels like I'm cheating here, since this one was written by Shakespeare, but it's not quite as well known as it ought to be. Also, for those who were wondering, St. Crispin's Day is October 25th.
Liam Neeson - Michael Collins (1996)
This is easily the most Irish speech you will ever see in your life. It ends with Liam Neeson headbutting someone, and it doesn't get any more Irish than that.
Christopher Walken - Poolhall Junkies (2002)
I think this is probably my favorite of the bunch. I doubt that would be true were it delivered by anyone other than Walken. Listen to how he says "jackals".
Sam Rockwell - The Winning Season (2009)
This one really isn't effective in terms of motivation, but I do really enjoy it. The mouth full of popcorn is a nice touch.
If you've been to a Stars game any time since 2004, you've probably seen the Kurt Russell speech from Miracle. It's a good one, but like Hoosiers, I grow tired of it. That is unless it is delivered by a 4 year old in a suit who taught himself the speech. Enjoy.