We already have the Promethian Mage (fire) and the Battle Geologist (Earth), now we need to complete the set with Water and Air themed classes.
For what it's worth, check out the mods index, there's two ice-based skills, and Wind Magic is a great air magic mod.
And I am currently working on both a water and air themed skill classes. I'll try to make them as interesting as possible.
Actually if you do have some good ideas for these mods let me know what you'd like to see in them and perhaps I'll make it a reality because I've only a few ideas as of now and its not enough for a complete skill class.