While I know the silliness of magic threads, when you have an interesting idea you can't help but want to write it down... and at least here it will be in the right place when the time comes.
Anyhow, my idea is for schools of magic based around infusing objects and materials with temporary power. I am not suggesting that these would be the only schools of magic; they would just be some of them. The good thing about these, though, is that they make for a type of magic that would take advantage of Dwarf Fortress' diverse material and object system.
I am assuming, for this, that all objects will have 'spheres' to an extent, representing their mystical association although they may not be useful (many objects may just have 'default' spheres inherited from their larger material or type.) This is of course something that will be valuable in many other aspects of magic, alchemy, and artifacts, not just here. For instance, a ruby might have a sphere of fire, making it suitable for fire-type artifacts, useful as an ingredient for fire-based magic, or whatever.
Spheres will have associated magical effects. These could then be drawn on by all sorts of types of magic and artifacts.
This form of magic, at least, would be divided into 'schools', which would be learned separately. The primary reason for this is to prevent players from too easily accessing all magical effects -- placing some limits encourages them to work a bit more to find the right materials that their particular school needs to access effects from a particular sphere, rather than easily grabbing any sphere they want. It adds more flavor and prevents anyone from becoming particularly powerful without heroic effort (or vast innate magical abilities), since they are limited to a small number of effects from that one school. Most adventurers, as I see it, would only have the potential to become 'hedge wizards' at best, and most infused objects that you can purchase or trade for would be similarly weak (though potentially still useful.) These are not artifacts.
A school will have its own innate spheres, representing the things it is best for. It will be limited to infusing a general class of objects -- there might be a school of wand-crafting that crafts wands out of wood, metal, or stone (or perhaps only one of those), and infuses those. There might be another school that infuses gemstones, or rings, or swords, or stranger things.
Each school will also have a power source, which influences what you have to do to infuse objects -- for instance, one school might be religious in nature, using prayer to imbue totems. Another school might draw on innate power (and be useful only to those who have such power); yet another might use blood, or things along those lines. If you use religion and prayer to infuse an object, the god whose power you draw on might influence the resulting spheres (and thus the power) of the end result.
These various distinctions will make it possible to procedurally generate a large number of different schools, based around grabbing things and gods that can be found in the civilization that developed that school, and refining them.
Note that the final spheres (and, therefore, the resulting power) of the imbued object would be both influenced by the innate spheres of the school you used to infuse it, and the type / material of the object. Since the objects a school can infuse are limited to one specific type, the spheres you can get are similarly limited. A school that uses alchemical procedures to infuse swords with fire powers might be able to vary their powers slightly by using different metals (or even wooden weapons), but the overall range of power they can access is constrained to include the inherent fire sphere of the school.
Schools might seem a little tightly constrained. However, it would also be possible to make schools into a higher-level organization which contains many specific 'procedures', so you could have a school which teaches the procedure to imbue rings with concealment powers, and a procedure to imbue totems with protective powers, or whatever. In this way characters could learn a wider variety of abilities at once (of course, schools wouldn't have to be limited to just this type of magic.)
A school would embody a larger body of magical and philosophical thought. Learning one school might help you a bit in picking up others, but they'd be separate -- it would be difficult to pick up many different procedures from different schools, and much easier to just focus on one school.
(How would a sphere's powers be defined? A sphere would need many different powers based on the situation under which those powers come into effect. For instance, a 'worn' power for if the sphere is used to infuse jewelry or armor, a 'weapon' power for weapons, an 'invoked' power for spells or wands of that sphere, a 'stationary' power for statues, totems, and constructed objects, and so on.)
Anyhow, I'm curious what people think. This is mostly just stream-of-consciousness, but I'm hoping some of the ideas here will be useful.