a lot of great ones have been mentioned...you basically can't go wrong with Bogey, and Bacall is such a babe, she steals every scene...
some newer ones:
LA Confidential - loved it...Guy Pearce is amazing...
Dark City - Sci-Fi-Noirish, what the Matrix borrowed from, only with better acting, and darker and less polished/geeky than the Matrix...

...and don't see the Black Dahlia-such a disappointment...though Hilary Swank was actually pretty good...

i liked the maltese falcon.

is sin city a film noir?

Yes.

Shadow of a Doubt(1943) and Spellbound(1945) are Hitchcock noir films.
The original The Postman Always Rings Twice(1946) is also very good.

but its also an action movie as well. i didnt think i would like it but it was actually quite good.

It's a neo-noir/post-toon-noir film. Very much like the Batman trilogy and even Who Framed Roger Rabbit.

Some of the David Lynch films are considered psycho-noir,
as is Fight Club.

BRICK

modern noir heh

strangers on a train is another hitchcock one.


also, the third man is a really great movie... maybe not film noir in the strictest definition but definitely noir-ish.

best genre description EVAH

Just thought of another really good movie Stanley Kubrick's "Killer's Kiss".

The Third Man has always been a favourite of mine.

Most of the ones based on The Hammet/Chandler/Caine books and stories are a safe bet. Farewell My Lovely (The 40s version and the later Robert Mitchum version both good), To Have and to Have not, The Big Sleep, The Maltese Falcon, Double Indemnity etc.

The Sweet Smell of Success is incredible, one of my favourite films in any genre.

Nice call on Touch of Evil, they don't come much better than that. And I used to love Dead Men Don't Wear Plaid when I was a kid, "Carlotta was the kind of town where they spell trouble T-R-U-B-I-L, and if you tried to correct them, they kill you." Funny stuff.

Joseph H. Lewis is a good reference... Gun crazy, The Big Combo, So Dark the Night...

Detour
Gun Crazy
Kiss Me Deadly

These are really good ones

More recently, Larry Clark's Another Day in Paradise.

Oh, and, yes, Sweet Smell of Success is quite quite good. Alexander Mackendrick knew how to use the black & the white, and his actors were perfect.