Which movie was just too ahead of its time to be appreciated?S

Sometimes a movie comes along that is just so radical, and so fresh, that nobody knows what to make of it. And then ten years later, you look back at it and realize that it was just too ahead of the curve. What's your favorite movie that slipped through the cracks when it came out, but would have been huge if it was only released a few years later?

Please include a picture, poster or clip for this movie. And please mention the Name and Why it was so ahead of its time. Thanks!