The final battle should just have the entirety of the les miserables soundtrack to playing in the background.

I do think it would be good to have some sort of song parody. You could even make a contest out of it or something to see who could write the best parody lyrics to Eyes on Me or something if you could get someone to sing it.

Edit: also, Do You Hear The People Sing parody could be cool. You could get everyone to try to send you audio clips of them singing and put it all together into one cheesy, beautiful mess.