Lock, stock and 2 barrels
That's a very good movie. I really enjoyed it. I also really enjoyed another Guy Ritchie movie, which has a similar feel (that I think was even better):
RocknRolla. Check it out if you haven't already seen it. Great soundtrack too!
Another really good movie, that got almost zero press and few saw, is
Blackthorn, starring Sam Shephard. It's a fictional theory on what happened to Butch Cassidy and the Sundance Kid in South America. It's a seriously well written and very entertaining movie, IMO.