STRANGE SPELL EFFECTS

Whether because they were unworkable, buggy, copyrighted or some other reason, these spell effects can be found in the text.rsc file, but didn't make it into the final version of the game in operable form (if you're running the unpatched version of the game, you can find some of these effects, but they don't work and most were removed by one of the early patches):

Morph Self: Causes target to transform into a creature or object selected by the caster. (actually made it into the release version, but was deactivated by one of the early patches because it didn't work)
Morph Other: Causes target to transform into a creature or object selected by the caster. You can see the effect at work with the artifact, "Wabbajack", but the effect is random.  I don't know why they couldn't get it to work in spell form. 
Morph Item: Causes target to transform into a creature or object selected by the caster.
Diminution: Causes target to shrink to half its normal size.
Astral Travel: Sends caster to the Astral Plane (as if Tamriel weren't bad enough...)
Etherealness: Turns caster ethereal, thus able to walk through walls (I think I can understand why this one was not implemented).
Wizard Sight: Allows caster's vision to travel separately from his or her body (don't you know this must have been a headache to code).
Darkness: Darkness created around target.
Telekinesis: Telekinesis allows the caster to move objects at a distance, by mental exertion (so what if there are 6 Ancient Liches guarding the lever?  I'll just cast a spell and be done with it.).
Intensify Fire: Caster may intensify the light of a normal fire.
Diminish Fire: Caster may dim the light of a normal fire.
Wall of Stone: Caster creates a wall of stone
Wall of Fire: Caster creates a wall of fire
Wall of Frost: Caster creates a wall of ice
Wall of Poison: Caster creates a wall of poison gas