My favorite sub genre. I would say: 1. Chinatown 2. No Country 3. Taxi Driver 4. Se7en 5. Body Heat Honorable Mentions: LA Confidential, Blood Simple, The Long Goodbye, Blade Runner, Drive, Sin City.
Yes, all 4 are considered neo noir. Usual Suspects is definitely an honorable mention. If you look up 1,000 lists of neo noirs, Chinatown is almost always considered #1 in the category, and I would agree.
The Dark Knight is also considered a neo noir, btw. Not many superhero movies fit into the subgenre, but TDK does.