For me there's been loads, but one I always remember is the original Lethal Weapon. It was class and the film lived up to it too.
Another one was the teaser for The Goonies, it spelt out the title from prior Spielberg/Donner films, excellent.
The teaser for The Doors, the silhouette of Val Kilmer walking down a corridor. (awful film though, pity)
The 25th anniversary trailer for Star Trek VI, it showed clips of the original series and first five films 'projected' onto the Enterpise.
The first teaser for Goldeneye, Pierce Brosnan walking towards the camera saying 'You expecting someone else?'
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"This is not a good idea, it is an awesome idea"
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