In Nomine SJG is a veritable smörgåsborg of this stuff. Liber Reliquarum is particularly chock full of awesome in this regard. Here, I'll just give you two:

Forty Slices of Cheese

"Compacted through the forces of time into a hard block of dark orange resin, the Forth Slices of Cheese are darkly malevolent. They were once given to a Remnant demon, homeless on the streets of America, by a government subsidy program. Indignant with the gift, she poured the last of her disdain for the human race into the slices, and an Infernal Intervention imbued them with the power to cause revulsion in anyone who holds them.

Anyone who touches the Forty Slices of Cheese must make a Will roll at -5 or become repulsed by the next thing he sees. This effect will last for a number of days equal to the check digit of the failed Will roll.

Note that, as a celestial artifact, the Forty Slices of Cheese are quite indestructible by any normal means."

"Violation"

"This aptly-named relic-weapon is nothing more than a holy parking meter. It was imbued with its special properties when the Holy Spirit intervened on behalf of a Malakite of Eli who tore it out of a sidewalk during a battle with demons. The parking meter was transformed into a celestial artifact on the spot.

Violation normally acts as a weapon with a Power of +4 and an Accuracy of -1; it requires the Large Weapon (Club) skill. It also requires a Strength of 6 to wield effectively (reduce Accuracy and Power each by 1 for every point the wielder's Strength falls below this minimum) because it's so heavy and unwieldy. However, when someone puts a coin in its slot (it takes nickels, dimes, and quarters), the Strength minimum disappears for the duration of the time on the meter, and it gains an additional 1 die Power!"

Girdle of Femininity/Masculinity

Who would make such an item, and why? Why does it only work once, and why does it inhibit changing back?

If you take the metagame factors into account it works, but as a real thing commonly encountered as a part of a treasure hoard, it's really damn weird.

Quote from: mcbobbo;590795Girdle of Femininity/Masculinity

Who would make such an item, and why? Why does it only work once, and why does it inhibit changing back?

If you take the metagame factors into account it works, but as a real thing commonly encountered as a part of a treasure hoard, it's really damn weird.

The ancients were a decadent lot.  In their boredom and debauchery, they created depraved magical items to inflict on slaves, or even themselves.  Such cavalier use of magic was an affront to the gods, and the so the ancients were cast down.

But seriously, it was probably made up just for a gag

Quote from: The Were-Grognard;590882The ancients were a decadent lot.  In their boredom and debauchery, they created depraved magical items to inflict on slaves, or even themselves.  Such cavalier use of magic was an affront to the gods, and the so the ancients were cast down.

But seriously, it was probably made up just for a gag

I think it was a metagame trap, and it speaks a little to the difference in culture, too.

But as a real item, I'd expect it to be reusable at the very least...

'Head of Vecna' is pretty good.

An amulet that cured dental disease called Tserc.

My players found a creepy painting that animated dead.  That was fairly normal for what it was, but then they took it back with them to their home base (a magic university) unaware of its powers.  And I decided on the fly it was an artifact, not a mere magic item...and had it animate the entire cemetery.  Ended up in a great pitched battle with the players fighting beside the professors.  Turned into a major plot point, with people arguing to use the artifact in a war effort, others arguing it was unethical to do so, a successful attempt to steal the artifact, and other great stuff in the campaign.

Ars Magica is a great font of inspiration for me. In one campaign the players found a large mirror which showed the presence of magic in its reflection. It could even spot regio and sources of vis. One of the magi took it with him on an expedition to search for a source of vis and promptly dropped it... and it wasn't actually his mirror.

Great source of intra convent conflict

And, a timely article from Wizards of the Coast.

Ok, well those are some pretty weird items, alright!

RPGPundit

A Detect Mountain Matrix with a range of 10 metres, in a boulder that was so heavy that had to be carried around in a cart.

Believe it or not, it came in useful in a scenario involving flying around a magical mountain that killed anyone who touched it in a very dense fog - the PCs flew the boulder very slowly and fired off a Detect Mountain every so often, to be GM's displeasure.

Quote from: soltakss;592798A Detect Mountain Matrix with a range of 10 metres, in a boulder that was so heavy that had to be carried around in a cart.

Believe it or not, it came in useful in a scenario involving flying around a magical mountain that killed anyone who touched it in a very dense fog - the PCs flew the boulder very slowly and fired off a Detect Mountain every so often, to be GM's displeasure.

Seriously? That one fucking takes the cake. Was there even any justification for why such an item would exist? Who the fuck would wake up one day and say "I'm going to make a huge ungainly item that can detect mountains; and only has a range so tiny that obviously anyone with the item would see the fucking mountain right in front of them in almost any circumstance"!?

RPGPundit

Surely there exists a subset of wizards to whom magic item creation is an opportunity to make 'great art' which has 'social meaning'.  Perhaps the mountain-detecting boulder is a sorcerous attempt at sociopolitical commentary.

My favorite part about Detect-Mountain Boulder's story is that it came in use and garnered GM displeasure (as if he was surprised or something!). Either a GM with a wicked sense of humor and good acting skills, or a GM who is truly a scatter-brain genius like a real wizard.

I stated up a Jack Chick Tract and the Dungeons & Dragons Roller Coaster Ride for 3rd Edition D&D.

New Wondrous Item: Dungeons & Dragons Roller Coaster Ride

This magic item appears to be nothing more than a theme park amusement ride based off of the world's most popular table-top role-playing game.  Anybody who sits in the cart (can hold 6 Medium-size creatures) will be transported to a specifically determined campaign setting halfway through the ride.  At this time, the surrounding environment will transform into a giant swirling tunnel (like a hypno-disk) while the cart tracks are suspended in mid-air.

The cart, and its tracks, will vanish from existence once the occupants are successfully transported.  The effect is one-way, and the stranded people must find an alternate means of getting back home.

Strong Conjuration and Illusion; CL 20; Gate, Hallucinatory Terrain; Price: 120,000 gp

New Wondrous Item: Chick Tract

This item appears to be a small book containing pictographs.  The story is usually of an impious or "sinful" person who learns the error of his ways and accepts God, or meets a fiery fate in Hell.  Anyone with an Intelligence score of 3 and can speak a language can comprehend a Chick Tract.  The Tracts' definition of a sinful person is incredibly broad, and brands huge swaths of religions (both in our world and the campaign setting), sexual orientations, ideologies, and scholarly thought with this label.

After reading a Tract, the person must make a Will Save (DC 12, reader can add her highest mental ability score modifier as bonus to save) or develop a burning hatred against the "sinful" group in the Tract and a strong desire to show the Tract to others and convert people to Chick's narrow religious beliefs.

The Tract can only affect a person once, and a person who succeeds on the save thereafter finds all Tracts to be ridiculous, bigoted, tripe (or a madman who has gone too far).  The Tract only works on readers who already have an unfavorable view of the group covered.

A Tract can be used an unlimited number of times.  Many of Chick's followers leave the Tracts in treasure piles, public areas, or between the pages of holy texts and library books in the hopes of spreading their message to as many people as possible.
Strong Enchantment; CL 13; comprehend languages, zealot pact, suggestion; 81,000 gp.

Quote from: RPGPundit;593346Seriously? That one fucking takes the cake. Was there even any justification for why such an item would exist? Who the fuck would wake up one day and say "I'm going to make a huge ungainly item that can detect mountains; and only has a range so tiny that obviously anyone with the item would see the fucking mountain right in front of them in almost any circumstance"!?

RPGPundit

It's possible to "botch" or roll a critical failure (or whatever term they're using these days) when creating a magic item in Ars Magica. And I could see something like this resulting from that process... it was meant to be a small stone with a really long range, but due to a miscalculation, the numbers for its range and size got switched around, with disastrous results... it instantly grew to enormous size, fell right through the laboratory floor, and three floors underneath, into the dungeon under the tower, killing nine grogs as it went, (a very inauspicious number!) and enraging the entire covenant....

(Didn't something like that happen with a botched fireball in Order of the Stick?)