Miller's Crossing is the Coen Brother's take on the 1930's gangster film...what's really notable about it is their use of language - they invented their own lingo for this movie. It's really remarkable in its cadence. Not to mention some incredible performances by Gabriel Byrne, Albert Finney, Marcia Gay Harden and, briefly, John Turturro. Their obsession with lingo is also explored, not as effectively, with The Hudsucker Proxy. Although, I love that one, too.
The theme of particular language (including repetitive quips), if you really pay attention to it, is apparent in all of their films, including The Big Lebowski, Raising Arizona, Fargo, Barton Fink, The Ladykillers...it's quite obsessive of them. Which, of course, just turns me on.

Cerebrally speaking.