I saw a Levis jeans advert at the cinema and I really like the dialogue. It's called "Pioneers, Oh, Pioneers" by Jean Rhys. From what I've found only a small portion of the piece is used.
Ignore the visuals in the youtube link, but it has the same words and voice as the one I heard.
http://www.youtube.com/watch?v=HG8tqEUTlvs&feature=related Pioneers! O Pioneers!
COME my tan-faced children,
Follow well in order, get your weapons ready,
Have you your pistols? have you your sharp-edged axes?
Pioneers! O pioneers!
For we cannot tarry here,
We must march my darlings, we must bear the brunt of danger,
We the youthful sinewy races, all the rest on us depend,
Pioneers! O pioneers!
O you youths, Western youths,
So impatient, full of action, full of manly pride and friendship,
Plain I see you Western youths, see you tramping with the foremost,
Pioneers! O pioneers!
We debouch upon a newer, mightier world, varied world,
Fresh and strong the world we seize.
Pioneers! O pioneers."