I was just thinking of something that would be awesome, although I'm not sure if I could help myself to pull it off.
I was thinking though, that if it's not already a part of the game (at least in some form), "Lisa's Song" from the movie should be in the game, possibly as a recital, or maybe even as her theme, if you're planning on having Character themes. I mean, yeah, it's relatively brief in the actual movie, but with some creative work, I think it would make a VERY awesome addition.
I did place it (known on the movie's album as "Doomsday is Family Time") into the game's soundtrack as Lisa's Theme, and would play in Lisa centric scenes, but currently, we haven't worked it into the game itself. Currently, only Bart and Maggie have theme songs, all the Final Fantasy characters get their respective theme from their original game also.