The Mark of Cain is a feature length doc about Russian prison tattoos that's now on Youtube in its entirety (73 min, below). The tattoos are the filmmaker's in to examine the Russian prison system, which is truly terrifying. Once I hit play, I couldn't stop watching this film - http://www.youtube.com/watch?v=s9JDJdaMs-Y
The fictional cousin to The Mark of Cain is Eastern Promises directed by David Cronenberg, which is about a British midwife's interactions with the Russian Mafia in London. I love this movie. Cronenberg has a unique skill when it comes to depicting violence to the human body, which has to come from all his years in horror. I think many people of my generation think of Tarantino as the handy man of entertaining on-screen violence (based on the ear scene in Reservoir Dogs alone) but I think Cronenberg's eerie mix of bluntness and understatement trumps Tarantino's pop sensibilities by a long shot. Not that I don't like a little pop.