I think Spiderman is an interesting idea. Julie Taymor did the Lion King and Bono & The Edge will presumably provide a driving rock score. Could be intesting.
Movies-turned-musicals (or in this case, comic-turned-animated TV series-turned-movie-turned-Broadway musical) are popular and often successful. Hairspray, for example, which went movie to musical to movie again.
Currently on Broadway there's Shrek and Billy Elliott.
9 to 5 the musical (with music by Dolly Parton, of course) is on its way. And there's even an
Addams Family musical in the works for 2010. There was a workshop of this show with Nathan Lane as Gomez and Bebe Neuwirth as Morticia. Now
that would be worth seeing.