Especially if we're restricting it to American movies (though then does Babel get it for having Brad Pitt in it, or what? That movie was mostly not in English, and has a Mexican writer/director team behind it). So I think this'll be a catch-all for me.

Anyway, in approximate order

The Departed/ 49 Up (tie)
Little Miss Sunshine
Brick
Inside Man
Borat
Street Fight, with Janey's rationale
Curse of the Golden Flower

still wanna see Casino Royale, Half Nelson, Children of Men, Pan's Labyrinth, The Queen, The Prestige, The Illusionist.