If Memento is considered noir, than so is Mulholland Dr.
I can't say not too much about the plot of this, not because it would ruin anything, but because it is mostly incomprehensible. The story starts simple enough, with an attempted murder and a case of amnesia, but everything gets very strange very quickly. Mysterious figures begin manipulating the production of a feature film, there is an incredibly strange scene at a playhouse, and, by identitis and circumstances have fractured and recombined. I'm at a loss as to describe exactly what it all means. Maybe it's a bizarre treatise on acting, maybe it's all a critique of Hollywood, maybe the first two acts are a dream of the main character, maybe the whole thing is a dream (but of who exactly?).
I'm going out on a limb here, but Mulholland Dr. might just be the most surrealistic film ever classified as a noir. With that said, it has all the classic elements, the tone of the whole film is pessimistic, there are few noble characters, there is mystery, there are even detectives. Even if you aren't a fan of David Lynch, this is really worth seeing. It's weird, it's disturbing, it's mostly incomprehensible, but it really is an excellent piece of fimmaking.