"The Stars my Destination" by Alfred Bester

that book is so crammed full of awesome ideas that it is impossible to single one out

The book series 'The Saga of the Seven Suns. When the leader of earth loses it completely and attacks their main ally and kidnaps their leader.

FIrefly - Just the whole show in general
Terminator 2 - The ending scene where Arnold goes into the lava thing
Mass Effect 3 - The Tuchunka mission
District 9 - The whole film was amazing, perhaps the ending scene (SPOILERS) where he ends up as a prawn sending his wife little gifts.

Ask me another day and I could probably list a completely different 5, in no particular order.

Matrix: "He is beginning to believe."

Metroid Prime: the part between descending onto Tallon IV's surface and when you beat Metroid Prime.

Serenity (River): "You've always take care of me. My turn."

Battlestar Galatica: the whole thing, for capturing and sustaining the feeling the entire human race is hanging over a precipice, and could fall at any moment.

Hitchhiker's Guide to the Galaxy (books): too hard to think of a favourite bit, there are too many.