I still think someone should do a magic system along the lines of the Pen and paper role playing game ars magica.

Basic premise: magic is changing reality through language. Therefore magic is categorized viatechniques (the verb) and forms (the noun): 

So all magic can be described as a combination of these two:

In Ars, the Arts available are as follows:

Techniques: Create, Destroy, Change, Perceive, Control

Forms: Fire, Water, Earth, Air, Mind, Body, Animal, Plant, Image, Magic

This is a great system, because it gives you enough permutations to create tons of interesting spells

some of the archetypical spells would be:

fireball : Create + Fire

mindcontrol: Control + Mind

Levitate/Fly: Control + Air OR Create + Air OR Control + Body

Invisibility: Destroy + Image

etc. etc. etc. A whole mini game in itself, with tonnes of interesting decisions. Magic as a building game, instead of basic commands.

Might be slightly complex to implement though, but if anybody could do it, it would be stardock!

Ars Magica! That was a blast as a PnP! And the magic system was really impressive. The freedom to create spells was really excellent.

don't forget to add that you could raise the difficulty of a spell you create to add properties to it.

For instance you try to learn a levitate spell. Control + air.

But the basic spell can just throw small things like rocks (you in fact created a "throw stones" spell)

But if you raise the difficulty level of the spell you could lift a person or fly or make ston flying at a very very high speed, thus creating a "1000 shards" spell.

A very excellent system.