Hm, I've seen some amazing movies, but they're nothing compared to Spirited Away. It was amazing. Wow! When I first saw it as a child, I couldn't understand the plot. Then, when I watched it last summer, I was surprised at how genius the movie actually is. It's still one of the DVD's that I kept. :]
Other than Spirited Away, I would also say Legion, Enter the Dragon, Rush Hour 1, 2, and 3, and Mulan.