And thus, a one-word movie quote meme. Some of these go back a ways. ETA: Added the answers to the ones no one had guessed.
Those that have been guessed so far:
1. Serpentine! - The In-Laws (the original)
2. Poppies! -- The Wizard of Oz
3. Precious. -- The Lord of the Rings
4. La-di-da. - Annie Hall
5. Silencio. - Mulholland Dr.
6. Superman. - The Iron Giant
7. Inconceivable! - The Princess Bride.
8. Ditto. -- Ghost
9. Plastics. -- The Graduate
10. Rosebud. -- Citizen Kane