The Big Heat (1953)

Another film noir classic from Fritz Lang. In The Big Heat, Gloria Grahame is not a temptress--well, only a little, anyway. Instead, she's the gangster's girl with her own moral code. When she steps outside the gangster's influence, she's punished with shocking violence.

Scarlet Street (1945)

Another pairing of Fritz Lang as director with Edward G. Robinson as the "little man" who turns murderous under the influence of a temptress. Scarlet Street was considered so dark and sordid that it was actually banned in several American states and cities, despite passing the Code board.

Film Noir: The Woman in the Window

The German director Fritz Lang was a very direct link between the German expressionist films of the '20s and film noir. Lang claimed that he fled Germany immediately after Joseph Goebbels invited him to become the head of a nationalized film industry under Nazism. In the US, he directed some of the classics of noir. It's possible that the genre reflects the disillusionment of German refugees like Lang and Billy Wilder when they discovered the same struggles for power in the promised land of America that corrupted their native European world.
  In The Woman in the Window, a mild-mannered professor falls under a woman's spell and finds himself enmeshed in a web of criminality, deception, and homicide. (The professor is our friend Edward G. Robinson, Keyes in Double Indemnity.) Lang got around some of the strictures of the Code by framing the main action as a dream.
  (You can find the rest of the film on YouTube following this initial excerpt.)

More Film Noir - Maltese Falcon trailer

Come closer . . . I'm going to tell you an astounding story . . .

The Maltese Falcon is, like Double Indemnity, one of the sources and pillars of film noir as style and genre. Even in the trailer you can see another of the hallmarks of film noir: Deception, duplicity, lies, and deceit. The typical film noir not only appears cynical and "dark," it unravels a complex plot in which nothing is as it first appears. (This may be another reason why retrospective narration is common in film noir.)

At the heart of the mystery, spinning out webs of deceit, there always seems to be a woman.
Mary Astor as Brigid O'Shaugnessy is one of the great deceitful femmes fatales of noir.

Sam: Was there any truth at all in that whole story?
Brigid: Some . . . not very much.

Film Noir

All Hollywood genres are significantly defined by their treatment of sexual themes and imagery. Musicals are traditionally built on fairy-tale romances and the display of women's bodies; the western often personifies the opposition between nature and culture as a complex heterosexual love story, troubled by an undercurrent of homosexual attraction.
   But film noir is an especially provocative case. Film noir plots are defined by their cynical view of corrupted heterosexual love, and by seductive female figures who betray male heroes--and arouse unsettling, ambivalent feelings in the audience. The dialogue in film noir is allusive and elliptical, and often comes across as more dirty-minded than any explicit depiction could be. The lighting characteristically suggests obscure forces lurking in the shadows. The world of film noir is steeped in fetishism: nothing is what it appears to be, and more importantly, nothing is as it should be. The prevailing moral order is both threatened and challenged by the eruption of desires that are usually repressed and unacknowledged. It's not a sunny picture.
   For our purposes, perhaps the most interesting aspect of film noir is that it constitutes a counter-tradition within Hollywood film: a self-conscious subversion of the image of American life that the studios generally sought to present. Central to that image is an abiding faith that men and women can find their deepest needs satisfied in romance, courtship and lasting marriage. Film noir proposes instead that sexuality is dangerous, unpredictable and often destructive.

A pretty good introduction to film noir can be found in the Wikipedia article on the topic.
A more extended treatment can be found at John and Stephanie Blaser's Film Noir Studies.