When I think of
noir it's an ordinary protagonist caught up in uncontrollable events, with some existential atmospherics.
Memento (2000) is my first choice. Rather convoluted, so you have to pay attention, but everyone I've recommended it to loves it.
Salton Sea (2002) is a "
neo noir" you can check out.
David Lynch's
Inland Empire (2006) and
Mulholland Drive (2001) play with the form, but David Lynch can be so exhausting. He's basically a moralist, though--similar themes.
Of course, there are the two films based on the Black Dahlia murders whose names I can't recall right now. I personally feel they're more costume dramas, though.
I also think
Children of Men (2006) has some
noir elements too.