I'd like to see conjuration spells lower your maximum magicka rather than work on a timer, similar to how sustained abilities worked in Dragon Age. Bound items could have a relatively low durability, and when they reach 0, they would be dispelled. Summoned creatures could fill up a certain amount of summon slots you get, and the number of slots you have corresponds to your level of mastery in conjuration. For example:
Novice: Can summon 1 novice level creature (I'd also like to see some novice-level creatures you could summon)
Apprentice: Can summon 2 novice creatures or 1 apprentice creature
Journeyman: Can summon 3 novice creatures, 1 apprentice creature and 1 novice creature, or 1 Journeyman creature
... and so forth. Basically, at master level you could get 5 "slots", and the level of mastery you need to summon the creature determines how many slots you take up. I'd really like to be able to choose between having 5 skeletons, 1 dremora lord or anything in between following me.
I'd also really like to see more animal-based summons, as opposed to necromancy and daedra-based summons. I know summoning daedra and undead isn't an inherently evil act, but I always felt a bit weird playing a nice conjurer with liches and scamps following me around.
What do you guys think?