This is a great idea. I was thinking the same thing the other night because in tactical battles I'm tried of having to choose my spell every time I cast it when I'm more often then not casting the same spell again anyway. The little pic of the spell book that you click when choosing a spell should switch to the icon of the last spell you cast, or have another few boxes next to it when you can drag and drop a couple spells like a "hotbar" so you can keep your most often used spells there for easy access.
