My favorite pre-1950 move is The Adventures of Robin Hood, a 1938 American swashbuckler film starring Errol Flynn, Olivia de Havilland, Basil Rathbone, and Claude Rains.
My favorites are the Hitchcock films - Rear Window, Vertigo, Rope, The Man Who Knew Too Much. Plus Mr Smith goes to Washington. I think I've seen Rear Window at least a dozen times. Check out this Rear Window time lapse.
I know this is a pre 1950s thread, but this 2005 movie, Brick, is a big fat homage to film noir.
It looks good, I'll have to download it. Thanks. Another great semi-recent film noir movie was "Body Heat". William Hurt and a then-very-sexy Kathleen Turner.