For instance crystal balls can be enchanted to become scrying balls. They would allow you to see forward into a dungeon or house via a disembodiment of yourself, it would be undetectable and freeze time while you were looking. You would not be able to interact with the world.
Or a cursed skull of darkness. It ould have one daily use and it would exhale a cloud of smoke that would let you escape.
Or perhaps a magical bag of holding.
Or a magical horn that would attract wild animals.
What do you think? Ideas for more?
Edit: Following the advice of zen1966 I will add ideas for more spells.
A weak seeker fireball that is made for long range attacks.
A curse that prevents you from keeping your aiming reticule steady enough to fight.
A curse to make your next attack misss.
A curse to Halve your attack strength. (melee and range)
A curse to halve your magic damage.
A spell to create a wall of ice that would have to be hacked through by enemies.
A spell to attach a red dot to nearby enemies so you can see them. (for dark dungeons)
A two-handed spell that charges 4 icebolts up slowly (three times as long as charging up one icebolt) but hen they could be fired off like a machine gun.
Well theres a few anyway.

Not to knock your idea, but imo we need more spell tomes a hell of a lot more than we need new items.

bump for my edit

For instance crystal balls can be enchanted to become scrying balls. They would allow you to see forward into a dungeon or house via a disembodiment of yourself, it would be undetectable and freeze time while you were looking. You would not be able to interact with the world. - Would slow the game down even more, but their is a similar spell that does a similar thing without freezing time, its called invisibility

Or a cursed skull of darkness. It ould have one daily use and it would exhale a cloud of smoke that would let you escape. - There is a Perk, Restoration I think that fills your health fully and saves you from death once a day when you are close to death

Or perhaps a magical bag of holding. - There are strength potions that help with this

Or a magical horn that would attract wild animals. - Just dont sneak in the wilderness, they will sniff you out

A weak seeker fireball that is made for long range attacks. - Not needed, as most can aim with the curser
A curse that prevents you from keeping your aiming reticule steady enough to fight. - would be frustrating
A curse to make your next attack misss. - same as ^

A curse to Halve your attack strength. (melee and range) - there are diseases that reduce certain skills/Health etc

A curse to halve your magic damage. - Called storm destruction Magic

A spell to create a wall of ice that would have to be hacked through by enemies. - This one I like, but conjuring an atronach does this for me

A spell to attach a red dot to nearby enemies so you can see them. (for dark dungeons) - This is not splinter cell tagging

A two-handed spell that charges 4 icebolts up slowly (three times as long as charging up one icebolt) but then they could be fired off like a machine gun. - I like this one, although if it takes 3 times as long you could just fire off 3 single spells instead, and with teh interupt/stagger perk for destruction this works better

Well theres a few anyway. - Keep them coming as I like a few of these.

I know one thing I would find useful. Boots of Falling. I know we have the ethereal shout, but it's just not the same.

Crafted staffs for magic and staves for melee.

like the ideas the game needs more intersting magic its been far too streamlined.

Don't give up hope on creative ideas for new features for anything, let alone Skyrim.

In our case, if Bethesda doesn't notice you, the modders will. It'll happen in some way or another eventually.

I'm not opposed to more magic items and spells, of course, but I agree with Karniest, on all points.