Here are a few:
Cloak of Misplacement–This cloak appears to be a normal article of clothing, but can never be found when the owner wants it.
Circlet of Basting–Causes the wearer’s hair to form a topknot suitable for use in spreading sauce on meat during grilling. Provides no protection from mundane or magical fire.
Tube of Controlling Vacuum Elementals–This strangely light, clear glass object confers total control over one vacuum elemental at a time…if you can find one.
Dust of Dustiness–Any object over which this magical dust is sprinkled will become dusty.
“Fairy Dust”–Actually powdered mica, this dust has no effect whatsoever on anything except to make it sparkle slightly, but it seems to cause players to develop the delusion that their characters should be able to fly with its aid. (Actual item from one of my campaigns–a female goblin used the stuff as a cosmetic before getting gakked by the party.)
Eyes of Myopia–These items are made of special crystal and fit over the eyes of the wearer, causing fuzzy vision and a -5 penalty to spot checks. Wearing only one of the pair causes the character to become dizzy and, in effect, stunned for 1 round. Thereafter, the wearer can use the single lens without being stunned as long as she cover the eye bearing the lens. Of course, she can remove the lens and see normally at any time, or wear both lenses to avoid the dizziness.
Figurine of Wondrous Power: Pewter Miniature–When activated, the Pewter Miniature acts in all ways like a tiny metal statuette of a character.
Metal Bands of Bilarro–When the proper command word is spoken and the square metal device is thrown at an opponent, it will summon all of the still-living members of all the failed garage bands Bilarro started before giving up heavy metal in favor of magic. Any persons conjured will be normal 0-level stock clerks, accountants, and middle managers. Of course, since the last band folded when Bilarro was a teenager, and he’s been dead for centuries…
Manual of Painful Exercise–This thick tome contains descriptions of exercises which, if undertaken, will prove excruciatingly painful and provide no health or fitness benefits whatsoever.
Mirror of Apposition–This mirror may be affixed to a wall and activated or deactivated by use of a command word. While the mirror is activated, any being which looks directly into it from less than three feet away will be instantly transported to a position directly before the mirror and no more than three feet distant from it.
Pluckstone–When roughly applied directly to the skin of a feathered creature, it will cause the feathers sprouting from the touched area to tear free from the skin and fall away.