I would like to see a spell set system, similar to what we have for weapon sets. Under this system, you could drag a single spell to a spell set, then drag a number of metamagic feats onto the spell set. The spell set can then be placed on the hotbar.
From now on, when you use the spell set, it casts the chosen spell, modified by the chosen metamagic feats.
As someone relatively new to casters, this would make my life much easier and make me much more effective at using my spells and mana. Not only that, with a little creativity it has the potential to be the framework on which you can build many cool things that might otherwise be difficult, like: contingency, a spell-twining feat that casts two spells at once, energy substitution, and all the other amazing and wonderful spell-casting innovations that Turbine has planned.