I know nothing, I didn't see anything, I wasn't there, and if I was there, I was asleep.

I'm really into mafia films like Goodfellas, Casino, Carlito's Way etc. However I've never seen The Godfather...which is a film I really want to see & hopefully will watch it soon.
One of my favourites movie is Casino, definitely recommend, personally I prefer De Niro's acting to Al Pacino.
Casino:

Another film I really like, starring Johnny Depp and Penelope Cruz is Blow, it is a true story based on the life of George Jung.

Blow: