I've always liked the way Elder Scrolls divides magic:
-Illusion (altering the way rooms or objects appear, perhaps unlocking a distinct set of build-mode items, offering an otherwise locked lot trait)
-Alteration (levitating, changing weather, transforming life state, etc)
-Destruction (hurting and even killing enemies, clearing the inventory of all non-enchanted items)
-Conjuration (summoning a familiar, demon, angel, extradimensional being, etc)
-Restoration (cure illnesses and altering moods, ending vampirism, bringing ghosts back to life)
-Mysticism (developing extrasensory powers, like telekinesis, clairvoyance, and mind control)
-Enchanting (creating improved items, like higher-quality foods or appliances that never break, or improving the value or number of uses of crafted items)
