As long as this has been brought back up to the top, add me to the folks recommending the Pusher films. I've heard about them for years, but honestly didn't expect much, but they're very good. The second and third films are very strong, with the third being the best of the batch. If you watch them close together, it feels like you're watching a good mini series.
I'd also recommend a British film called Shifty, similar feel to it.