The rules: First and foremost, no musicals. It would be too easy for them to dominate this list, and they honestly deserve their own list. Furthermore, no 'scored' scenes. That's why you won't see Goodfellas or The Graduate or Harold and Maude on this list. On this list the characters must be interacting with the music. Without further ado...
10. Beetlejuice
9. Risky Business
8. Wayne's World
7. Big
6. Back to the Future
5. Ferris Bueller's Day Off
4. Magnolia
2. The Shawshank Redeption
1. Casablanca
Of course that's only a few of many great musical moments in movies? Which moments did I miss? Feel free to add those below.