And there's that bizarro concept album from the 70's, "Spiderman: Rock Reflections of a Superhero."

And here's something google just turned up for me that I knew nothing about:  some guy/group known as "Ray Wall Band" put out "The Fantastic Four Song" on iTunes last year, which wound up selling more than the movie soundtrack.  And his/their latest effort is, wait for it, "The X-Men Song:  A Superhero Rock Opera."

A quote from the MySpace page (http://www.myspace.com/raywallband):

"The X-Men Song: A Super-Hero Rock Opera" is conceived, produced, and recorded to be, in musical terms, the equivalent of a major super-hero movie experience: equal in power, equal in fun, equal in coolness, and equal in technology.  In plain English, it is the most ambitious super-hero song ever recorded!   
 Ray Wall Band's new single is a nine minute state of the art journey deep into X-Men territory which includes voice actors, choirs, multiple music styles, special effects, and more.  The music for this work took over 30 hours to record, used over 60 tracks, and required the engineers to approach the music like a film. 

Who knew?

Christopher