So the Elemental Savant Prestige Class in Complete Arcane mensions focus in elemental damage types that go beyond the norm; quote "...bone, metal, nether, plasma, and wood.... Determining the sort of damage each of these elements does, and how that type of damage interacts with the four recognized types of energy damage is the crux of this design process."
Bone, metal, and wood are rather self-explanatory in that they'd be more physical damage types; but has anyone ever looked into nether, plasma, or other exotic energy forms as magical energy?