Not really a fan of musicals, but there are a couple that I like. Sweeney Todd is enjoyable (Johnny Depp is no George Hearn though, so worth looking for the original cast film. It was on Netflix, not sure if it still is). Anyway, single moment, the "By The Sea" scene is fantastic, if only for Depp's absolute indifference through it all.
Repo: The Genetic Opera I like start to finish (well, there's a couple songs I could do without), but "Night Surgeon" scene is one of my favorites, owing to Anthony Stewart Head's astounding voice, as well as some industrial street-cred with Ogre (from Skinny Puppy) playing Pavi. The ending, from "Chromaggia" on is fantastic.
Oh, and have you watched "Dr. Horrible's Sing-Along Blog"? You should. Neil Patrick Harris brings it, Felicia Day isn't bad, and Nathan Fillion is surprising. Not surprising that he's awesome, just that he sings as well as he does.
Oh, and as a Buffy fan, I feel compelled to mention "Once More With Feeling", but I'm not sure if it really works without knowing the characters, and where they are at that point, emotionally. Piece to a much larger puzzle.