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