Yes there is a Finding Nemo musical. It can be seen down at Animal Kingdom at WDW. It actually is really cool...combination of puppetry and hand puppets.
I didn't mean that in an insulting way, I just was kind of surprised they would try to make a musical out of that film, considering that it's Pixar and when I think of Pixar, I don't think of musicals. 
That's all.
when somebody love me,
everything was beautiful.
Every hour we spent together, lives within my heart....That not ring a bell? Yeah, I know, not really a musical number, just a little montage song, I guess.
As for musicals I've seen:
Billy Elliot- For a story about a boy from County Durham during the miners' strike learning how to ballet-dance, it's a surprisingly good story! And the musical numbers are pretty intense and fun... Especially the one from when he discovers his best friend is a casual transvestite, and they have a whole musical number about dressing up as women (complete with dancing disembodied dresses).
The Lion King- Oh man... Probably the first proper play I ever saw, and it's stuck with me always. Everything was just so well done and thought out, and the costumes were brilliant... Except for Timone and Pumba. In a play where the costumes were primarily head-dresses and makeup, they looked almost like something out of a panto.
The Lord Of The Rings- Another surprisingly good musical. Huge budget and amazing effects (I still have nightmares about when Shelob appeared), and really good songs too, especially "The Road Goes On", "The Cat and The Moon" and "Lothlorien"
I've seen some other musicals, including bits from DVDs of Cats, Into The Woods, and plenty of pantos (Though I hardly consider pantos as theatre, let alone musicals), but I've forgotten them all. My parents aren't that into musicals, they prefer regular plays.
