Given the metaphysical framework, it hasn't been too hard to fill out those lists, either. Add in the basic D&D assumptions about what magic-users ought to be able to do, and what I get are a bunch of questions: "What part of their soul would sorcerers use to do damage? How would that work?" "Should I have a spell like light? What's the game function of that spell? Is there another way to get the same effect that makes more sense in the metaphysics?" And I've been giving some thought to what would be useful in a social game that's not already in D&D, and what's in D&D that would be too useful in a social game. I've broken charm, for instance, into several spells, depending on what parts of people's souls they manipulate, and exactly what kind of effect they produce.
All this means, though, that the magic system is going to be very setting specific. It's possible that you could use it with a different setting, but I'm not sure that you'll be able to use it without the very specific approach to souls and other such things that I have in the setting I'm using. I'm not sure yet just how hard it would be, but there are going to be at least a couple of spells that just won't make any sense unless you know, for instance, certain things about the way that the magic metaphysics interacts with gender.
Which I worried about, until I realized that, hey, this is D&D. People can just take out the spells they like and forget the ones they don't. Or ignore the magic system entirely, and just borrow the other subsystems. If I was doing something really new and interesting with the mechanics of the magic system, I'd be more concerned with making it setting-independent. As it is, I'm considering stealing Arcana Evolved's "readied spells" concept, and perhaps even combining it with a "roll to cast" option, but nothing truly revolutionary. And it doesn't need to be.