Fargo.
This movie has a creepy murder mystery vibe to it. It is unique in that it does not have your typical "A personality" hero cop/detective/rebel who pieces together a puzzle to figure out the murder. Instead you have a pregnant police chief who you think unlikely to fit the role. There is no suspenseful moment in which all the pieces come together to solve the puzzle. It happens all very subtle and quick. The movie is a recipe of erie backdrops and scenarios which sort of send chills down your spine. The movie ends with questions unanswered, which I think is a sort of original way to complete the project.
Big Lebowski.
This movie is a comedy/drama. It has some very funny moments in it, but is clearly presented on a serious note. The delemma in this movie is a man who is on a mission to fix something that was not right. His life was invaded by a circumstance that had nothing to do with him, yet was thrown at him because he shared the same last name as the subject at hand. The scenarios are comedic and cleverly put together, and the characters mesh with good chemistry. The ending of the movie leaves you with no resolve, but it has a feel good twist to it.
Lebowski differs from Fargo in that it has a different plot and cinematic formula, yet both are similar in that they give you dynamic aspects of the storyline and have unpredictable scene sequences. I believe this is the genius of the Coen brothers. They know how to take 2 or more movie formulas and mix them together in a dynamic way which contradicts "hollywood" politics that say how a movie should come together. Neither movie really made any sense, but that is what makes them great. They are unpredictable and original.