Layer Cake
Heist (Gene Hackman)
Spartan (Val Kilmer)
My benchmark for a good flick is that if you stumble across it being broadcast - or on cable, however you want to say it - you watch it no matter how many times you've seen it. All three of these fall into that category for me.
Spartan is good. Anything by David Mamet qualifies as “cult.” Also, stuff by Michael Mann, “Heat,” “Collateral,” and I think he did “Manhunter,” too, the first Hannibal Lechter flick.