[On a formatting note: I've tried to both embed the trailers (where possible) and link to the trailers someplace where I know they won't be pulled. If there's no embed, blame YouTube. Just click the link on the movie's title and you'll get it.]
1. Kill Bill (2003)
This would be the original teaser clip, released even before the film was split up into Volumes 1 and 2. It's an absolute knockout, instantly making "The Battle Without Honor and Humanity" an iconic piece of moving scoring and time-out music at your local sports arena. The choreography of the clips to the music might be the best I've seen in a trailer, and while "the 4th film by Quentin Tarantino" is self-aggrandizing, it's Tarantino. Would we expect any less?
Awesome trailer attributes: cool song/score; iconic performance; teaser
2. LOTR: The Two Towers (2002)
Once again, we encounter Clint Mansell, whose Requiem for a Dream piece "Lux Aeterna" was fleshed out into this rousing, oft-repurposed orchestration that practically blasted my face off for the latter half of 2002. Of the three Rings trailers, this one probably had the most anticipation going in, and it delivered the best of all of them. Note the strategic decision to reveal one fairly significant spoiler (Gandalf's alive!), which, given that 50% of the audience already knew (anyone who read the books or a casting report), probably wasn't that big of a risk. But it was crucial to allow McKellen's voiceover into the trailer -- no one sells a line like "the defenses have to hold" better.
Awesome trailer attributes: cool song/score; iconic performance