Bloodcookie
Explorer
I couldn't find another thread serving this purpose, so... post spells and magic items of your own design, for critique and general sharing! 
Here are a couple of spells and an item, all inspired by characters that I've conceptualized but never actually played:
Hermal’s Paraöntic Extraction
Conjuration (Summoning)
Level: Sor/Wiz 5
Components: V, S
Casting Time: 1 standard action
Range: Close (25 ft. + 5 ft./2 levels)
Target/Effect: One creature
Duration: Instantaneous
Saving Throw: Will negates
Spell Resistance: Yes
This spell creates a resonance between the targeted creature and its analog in a parallel multiverse, drawing the two into simultaneous instantiation at the target’s location. A successful Will save by the target successfully maintains its ontic autonomy, and no further effects of the spell occur. Otherwise, the resulting interference does 1d6 damage to both the target and its analog, before shunting the analog to a random square adjacent to the target. The cognitive dissonance that results from encountering its parallel self causes the analog to enter a temporary fugue state, in which it will make a full attack upon the target (The analog possesses equipment identical to that carried by the target). After doing so, the analog is immediately restored to its multiverse of origin.
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Rod of Metamagic Switcheroo
This rod functions only for spellcasters who prepare spells. The wielder of this rod may cast any spell that has been prepared with a particular metamagic feat as if it had instead been prepared with any one other metamagic feat the caster possesses of equal or lesser spell slot adjustment. The spell slot of the converted spell remains the same as when it was prepared. For a spell prepared with multiple metamagic feats, the rod’s power may only be applied to one such feat, and the feat that it is converted to may not be the same as a feat already applied to the spell.
Strong (no school); CL 17; any two metamagic feats; Price 19,000gp
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Dulang’s Remorseful Recoupment
Abjuration
Level: Sor/Wiz 9
Components: V
Casting Time: 1 standard action
Range: Touch
Target/Effect: 1 touched magic item of the caster’s creation
Duration: Instantaneous
Saving Throw: None
Spell Resistance: No
Originally developed by the mage Dulang, an artificer known more for his prolific output than for the quality or usefulness of his creations, this spell was a result of the pangs of good sense that frequently struck him upon completing yet another of his novel, ingenious – yet only marginally useful – creations. With this new dweomer mastered, he was able to maintain his reservoir of personal energy, and continue his fanciful manufacturing for years to come (it is speculated that one item which survived the quality-control process and made its way into public circulation was the overly-complicated Rod of Metamagic Switcheroo…).
This spell allows the caster to reclaim the XP expended in crafting a magic item, eliminating the item’s magical powers in the process. The caster simply touches the item while casting this spell, and all XP spent in crafting it are added to the caster’s total, while the item itself is affected as if by Mordenkainen’s Disjunction. Note that the caster can only reclaim XP from items he or she personally crafted.

Here are a couple of spells and an item, all inspired by characters that I've conceptualized but never actually played:
Hermal’s Paraöntic Extraction
Conjuration (Summoning)
Level: Sor/Wiz 5
Components: V, S
Casting Time: 1 standard action
Range: Close (25 ft. + 5 ft./2 levels)
Target/Effect: One creature
Duration: Instantaneous
Saving Throw: Will negates
Spell Resistance: Yes
This spell creates a resonance between the targeted creature and its analog in a parallel multiverse, drawing the two into simultaneous instantiation at the target’s location. A successful Will save by the target successfully maintains its ontic autonomy, and no further effects of the spell occur. Otherwise, the resulting interference does 1d6 damage to both the target and its analog, before shunting the analog to a random square adjacent to the target. The cognitive dissonance that results from encountering its parallel self causes the analog to enter a temporary fugue state, in which it will make a full attack upon the target (The analog possesses equipment identical to that carried by the target). After doing so, the analog is immediately restored to its multiverse of origin.
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Rod of Metamagic Switcheroo
This rod functions only for spellcasters who prepare spells. The wielder of this rod may cast any spell that has been prepared with a particular metamagic feat as if it had instead been prepared with any one other metamagic feat the caster possesses of equal or lesser spell slot adjustment. The spell slot of the converted spell remains the same as when it was prepared. For a spell prepared with multiple metamagic feats, the rod’s power may only be applied to one such feat, and the feat that it is converted to may not be the same as a feat already applied to the spell.
Strong (no school); CL 17; any two metamagic feats; Price 19,000gp
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Dulang’s Remorseful Recoupment
Abjuration
Level: Sor/Wiz 9
Components: V
Casting Time: 1 standard action
Range: Touch
Target/Effect: 1 touched magic item of the caster’s creation
Duration: Instantaneous
Saving Throw: None
Spell Resistance: No
Originally developed by the mage Dulang, an artificer known more for his prolific output than for the quality or usefulness of his creations, this spell was a result of the pangs of good sense that frequently struck him upon completing yet another of his novel, ingenious – yet only marginally useful – creations. With this new dweomer mastered, he was able to maintain his reservoir of personal energy, and continue his fanciful manufacturing for years to come (it is speculated that one item which survived the quality-control process and made its way into public circulation was the overly-complicated Rod of Metamagic Switcheroo…).
This spell allows the caster to reclaim the XP expended in crafting a magic item, eliminating the item’s magical powers in the process. The caster simply touches the item while casting this spell, and all XP spent in crafting it are added to the caster’s total, while the item itself is affected as if by Mordenkainen’s Disjunction. Note that the caster can only reclaim XP from items he or she personally crafted.