Part of the Keepers (which I will likely be releasing as a standalone in order to drum up interest in the Keepers) will be a list of Alteration spells, as alteration is by far the worst school of magic and i want to make it a viable primary skill. Here are my ideas so far (many of them I have made, which will be denoted with an asterisk)
Irritating Swarm* - summons a cloud of bees that prevents spell casting inside of a 30 foot radius, including the caster himself
Protections from Frost/Shock/Fire/Magic 20-40-60-80%* - these also make it harder to cast spells of the appropriate element
Slow Time to 95% - 90 - 80 - 65 - 45
Portals* - manipulate the properties of space itself
Telekinetic Strikes* - lift and throw objects up to 6 - 12 - 20 - 32 - 45 - 60 Mass units and throw them at a target for physics based damage
Magedark* snuffs out the nearest light source
Army of Air* - creates six warriors out of thin air that to 0% damage at Adept levels, 10 at expert and 20% at master. The warriors level with the player, so six at 20% is like having a really awesome summonling.
Ghostly Prison* - summons a cage around the target, eliminating their melee abilities

was wondering if you guys had any other ideas for Alteration spells.

Water walking, if it can be done.

A friendly paralyze spell. So you can stop NPCs rushing recklessly to their deaths. And area paralyze (with friendly version). These would obviously be for high levels.

Open and close locks.

Spring trap, reset trap.

Speed allies.

Shield allies!

Create barrier. You could put it across a doorway to keep things out, or in. Ideally it could take damage and disappear if hit.

Pull (distant) lever.

Someone did water walking, I've no idea how.

There is water walking effect in creation kit (you can look at vampire lord abilities - one of them has it)
Someone also did ice barriers (and they even can be destroyed by hitting)
Distant activators is a very interesting idea, with it you can pull levers, open doors, and maybe even more. That will be very interesting to see it working