[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. Signs (2002)
Say what you will about the final product of M. Night Shyamalan's movies -- and I actually quite liked this one, despite the H2Oh-come-ON denouement. Shyamalan trailers are almost always better than the movies because you don't need to go beyond the smoke-and-mirrors that are his bread and butter. Here, the pseudo-archival footage of the crop circles combines with the excellent Hitchcockian score (while making sure to sell Mel Gibson's face back when there wasn't a downside to that) to deliver an almost perfect supernatural tease.
Awesome trailer attributes: teaser; creep-tastic; cool song/score
8. X2: X-Men United (2003)
I must've geeked myself out dozens of times on this trailer (the second clip after the decent-but-not-great teaser) in the weeks leading up to X2. Just lots of good decisions here, from allowing Brian Cox's character to deliver the bulk of the exposition to the focus on the sheer number of characters in the movie (always a strength of the X-Men flicks). Bonus points for including as many shots of sexy Aaron Stanford shooting fireballs as humanly possible.
Awesome trailer attributes: iconic performer