Something playing on the idea of 'thaumaturgy'? Mind you, Terry Pratchett already did that...
Should be an interesting project. Are you looking at what powers magic in different universes, such as those that depend on internal magic of the user, on chants and incantations, on supplication to the gods, on drawing external power from the natural world, or something else? I know in one of my universes magic is blood-based, basically inherited, although there's an external type of magic generated by the gods and the land, but that's Magic as a being and not the magic people can wield (not that they wield it - magic is banned in one country, so few people even realise they have it - it appears like talent in certain areas, keeping itself hidden so it can survive in the bloodline).
Hey, what about 'genetic' magic? That's probably how Harry Potter magic works, unless it's based on an idea of every living being having magic - sufficient magic creates a Muggle-born. Genetics explains squibs though...
Okay, shutting up now.