At the top of my head some mob or crime movies:
Analyze this
Analyze that, both are comedy but I liked them
wannabes
rise of the footsoldier
Il camorrista, look at Furrio's thread he posted the movie there
Mean streets
snatch
lock, stock and barrel
Serpico
il capo dei capi mini series
boss of bosses
the bonnano movies
Witness to the mob
Chicago overcoat
Kill the Irishman
Rob the mob
Gotti

Not all of them are real mob movies but they have the element of crime in them. And most are under the radar except for the British ones.