One actor, one set. It's a premise that's been done before, but the effectiveness that it's pulled off with in Buried's story of a man who wakes up in a coffin is to be commended. The film never cuts away from the coffin, always staying with Ryan Reynold's character as he goes through a panoply of well-acted emotions and engages in a surprising amount of thrills considering his predicament. Telling you much more would give away whether he lives or dies, so I'll just say that this movie left me pretty speechless for a while afterwards. Terrifying.
