Strange how that happens, I had my mind set on a Denzel (who, by the way, is the man) movie at this slot. Luckily it's not Training Day, although I do like that one quite a bit.
This is probably my favourite Denzel movie. It's based on a true story, stars Russell Crowe as well as Denzel, and combines good acting with a very interesting storyline. Frank Lucas was one risk-taking mofo, and it paid off for him until he was eventually incarcerated for a good number of years.
OH, almost forgot - this movie has one of the best soundtracks I've ever heard. It's pretty much all old r'n'b and jazz type stuff. Definitely helps with the setting and atmosphere.
American Gangster