I can think of many songs... but I don't want to post them 'cause I don't want people to steal my MMV ideas. *paranoid*
But I'll say a few anyway...
"You Save Me" (I *think* it's sung by Kenny Chesney)) kinda fits Gold and Crystal in my opinion. It's about how the singer is reckless wanders around a lot, but his girlfriend/wife/whoever it is loves him anyway. So the theme fits... even though Gold would probably rather saw off all his toes one-by-one with a nail filer than actually say anything that's in that song.
I heard a song called "Frozen in Time" that fits Mask of Ice, like, perfectly. The artist is "Funker Vogt" or something.
And then there's a song called "Mask" that would fit either Blue (girl) or Silver. The artist is "The Gypsy Butterfly."
Nelly Furtado's "Maneater" fits Blue (girl) a little bit.
And "At the Beginning" from Anastasia is PERFECT for Ruby and Sapphire.
And I heard a song that I think would fit LuckyShipping, if I was a LuckyShipper. It was called "Because You Loved Me." I don't know the artist... now that I think about it, maybe it could be ChosenShipping too.
There are other things that I've made MMV's for or am making MV's for... but I don't want to type any of them.