Insomniac should write a book on how to make an exciting trailer because they consistently manage to get my blood pumping whenever they release one.
Take, for example, this new Ratchet and Clank: A Crack in Time trailer released yesterday at gamescom. It has a curiousity piquing opener, followed by the necessary amount of dramatic voice-over narration and a lot of things exploding. I want this game. I want it so bad that I can smell the cellophane wrapper that my copy will come in.
It's really quite a good trailer, I assure you. You should follow the link and check it out.