Greatest war movies, that I know of anyhow;
Saving Private Ryan
Black Hawk Down
Full Metal Jacket
We Were Soldiers
Three Kings--border-line war movie
Braveheart--kind of a war movie
Enemy at the Gates--was pretty good too
Also, Tigerland, which isn't a war movie, but it is about a war, is actually pretty good too. Bozz kind of reminds me of Wooz, and I liked Bozz.
I can name plenty more, but I don't want to sound like a war fanatic.
Greatest "American" horror movies, since Kharn says no good horror movies come from America;
Mostly what welsh posted (horror movies)
Alien-all of them
Night of the Living Dead (the original)
Jurassic Park was pretty good
Faces of Death series--quite disturbing. American?
There are a lot more, but I won't name them since they tend to draw to the teen and younger age crowds
Oh, and people who said Blair Witch was crap, yeah it is, but watching it for the first time, the real way a horror movie is supposed to be watched (alone or with a girl, in the dark, sound up, door closed, and at night) makes it a bit scarier. Although, it wasn't what I expected it to be.