Signs had a very moronic ending.

On the newer side of things, I Am Legend's ending was bad, but made worse by the fact that the novel had an excellent, poignant, and ironic ending.

I also have to simultaneously scoff at and agree with those who have little patience with oscar-baiting films with "low impact" endings like Lost In Translation. Although I think that movie is one of the best I've ever seen, some part of me wished for more. I guess that's the point.

Also, see anything that M. Night has made post Sixth Sense. While I do think that Unbreakable had a rather succinct view of comic-book relationships between the hero and the arch-villain (always something that interested me, especially now that The Joker is being revived on the big screen), I didn't like how it was presented. The Village was predictable, Signs was absolutely retarded and Woman In The Water (or whatever) was brutal in every way.