Perhaps my all time favourite is Carl Sagan's "Pale Blue Dot" - I have already included it on this post (Cosmos, then & now), so you can see it there as well.
The Pale Blue Dot
Carl Sagan reads a passage from his book Pale Blue Dot as images of Earth from space are shown. His use of language is inspiring and emotional. His message is one for all people. The entire passage can be found by clicking here on the Planetary Society web site.