The open/lock spells were good for my mages I am disappointed that they're gone.

Unlock spells, cure disease and weakness to magic/elements spells, oh and spell making of course.

Bound Armour
Variety of Daedra you could summon
Mark/Recall
Almsivi/Divine Intervention
Levitation
Open
Waterwalking

AOE destruction spells, I loved in oblivion sending a cloud of frost towards enemies, now I have to get to level 100 destruction for an AOE destruction spell which takes 3 seconds to cast.
I dont like destruction in skyrim as I have to be very accurate with my spells.

Cure Disease

I miss dspell, cure disease and unlock and that's about it. I really DO NOT miss the damage attribute spells. I really really hated those. I actually way prefer animating a body to summoning one out of thin air. More Daedra summons would be nice (( in fact. just more Daedra in general)

Unlock is my highest priority alongside bashing chests open with weapons. Every archetype build should have its own way into the loot containers.

I miss the "lock spell" not that it was very useful becaue back in Morrowind thigns couldnt open doors any way but would of been useful in oblivion and Skyrim

Absorbing Health on touch or as a ranged Mysticism spell.
I should not need an enchanted weapon to leech the life from my opponents, or have to resort to becoming a Vampire.

Yeah, open/lock with Skyrim's npc mobility would be so cool... unless they make the guards omnipotent and they teleport through doors which would svck...

Fortify Skill: Would be fun to have access to some fortify skill spells in Skyrim, they would finally be actually useful at higher levels.

Open, Waterwalking and most of the utility spells in general.

Silence, for abvious reasons. It could finally turn the tide on those really powerful mages one can encounter later in the game. Should be a high requirement effect of course.

Bound Armor.

Dispel, on others and self.

Never been much of a fan of the levitation spells, but I haven't anything against them either. It would take away a lot of exploration if one decided to use it, but this would be one of those things where the argument "don't like it, don't use it" actually is valid. I highly doubt enemies would use it, though having certain bosses use it could be a fun challenge.

Absorb spells were good to have and gave restoration in Oblivion some useful offensive spells.

More summonable creatures and weapons for flavor.