Just saw these two movies. The latter was the inspiration for my tag.
Infernal Affairs: The movie is about an undercover cop working for a gang and an undercover gangster becoming a model police officer in order to give their respective organizations a leg up. The departed was based on this but for some reason it tried to mash the plot into boston and that failed but you don't have to worry about the story being ruined for you when you watch this. Nearly every scene is handled better in this. For example, the gang-mole/police-mole drug exchange scene actually was exciting. Felt flaccid as hell in the departed. If you've never seen the departed before though, definitely check this out. One of the better crime movies that I've seen. Very unique premise and does it well too.
Hustle & Flow: literally prostitute yourself if you have to in order to see this. WOW. OMG. It is the best music movie I have ever seen. The movie is about this pimp that tries to get into rap and the obstacles that he encounters. It has some of the best rap I've ever seen in a movie too (pretty sure it's all original too). Like I said, sell your butt cherry for this movie. I can't tell you more about it without spoiling it.