In fact, wow, check out Superhero Songs and go check under S for Superman. Wow. For those interested, aside from Supes, Batman, Captain America, and Spider-Man have far and away the most songs about them. Still, Batman, who has the most, has about 15 songs listed on that page, whereas Superman has nearly fifty.
So what is it about him that makes us write songs about him? I mean, I've actually written a paper about the development of superheroes and why they came about when they did, and Superman is pretty much the first, and he's certainly a part of the American (and perhaps the world's) consciousness, but I find it fascinating that we keep writing songs about him. I wonder what it is, the hero or the alienation (both literally and figuratively), that gets us. I mean, music is a powerful thing. Why do we feel the need to put this character to music?