What are your "must-watch" movies?

I'm not a huge movie fan, but I want to broaden my horizons a bit. I'll offer my list (that I've rewatched so many times I'm a bit tired of them):

• Young Poisoner's Handbook
• Full Metal Jacket
• Life of Brian
• Holy Grail
• Sunset Boulevard
• Curse of the Golden Flower
• The Nightingale
• Downfall
• Amadeus
• Once Were Warriors
• Dusk to Dawn