I'll start.
1. West Side Story (always a Jet...)(LEONARD BERNSTEIN!!!!) Between James Dean and The Jets... Doomed to be a smoker. IMPACT. https://www.youtube.com/watch?v=c9z33lasnkU
2. The Kids Are Alright (movie in it's entirety, thanks YouTube: https://www.youtube.com/watch?v=l3cFRUZgS9E)
3. Rocky Horror Picture Show. I'm all Riff Raff, But I used to tap like Columbia. https://www.youtube.com/watch?v=umj0gu5nEGs TP, Squirt Guns, and cosplay.

1. I'm Brad, and I can't move my socks! Don't forget toast.
2. Dr. Horrible's Sing-Along Blog (technically a mini-series, but best watched as a single video.) https://www.youtube.com/watch?v=QBteWFueKlg
3. Sweeney Todd

Honorable mention to The Producers, Chicago, Labyrinth, Nightmare Before Christmas, The Mask, Little Shop of Horrors, Blues Brothers, & O Brother, Where Art Thou?.

1. Little Shop of Horrors (1986) The second one.
2. Rocky Horror Picture Show (1975)
3. Sweeney Todd (2007)
Honorable mention: Tenacious D and the Pick of Destiny (2006)

I have always liked Into The Woods. From the first time I saw it on campus at college.