OK, you know all those brutal old-school cursed items? Bowl of watery death, rug of smothering, etc? i always hated them, but I think I came up with a twist that allows me to use them in good conscience.
Every cursed item, when its curse is thwarted, becomes a useful magic item for the user who mastered it.
For me, this suddenly transforms "evil DM" items into "interesting treasure" items. Cursed items are kind of like intelligent items: if you prove stronger, they can be useful tools. But instead of making a contested ego check, you conquer the item by succeeding at some task that's specific to the curse.
I'll use examples from 3e for cut and paste convenience, but every edition has pretty much the same list of gotcha items.
Broom of Animated Attack: This item is indistinguishable in appearance from a normal broom. It is identical to a broom of flying by all tests short of attempted use.
If a command is spoken, the broom does a loop-the-loop with its hopeful rider, dumping him on his head from 1d4+5 feet off the ground (no falling damage, since the fall is less than 10 feet). The broom then attacks the victim, swatting the face with the straw or twig end and beating him with the handle end.
What I'd add to this: the rider can make difficult Ride checks to stay aboard the broom. Several successes will "break" the broom. From then on, it will be an exceptionally loyal Broom of Flying for this user, but will act as a Broom of Animated Attack for all other riders.
I'd further posit that one of the items needed to create a Broom of Flying is "the soul of a steed." Brooms of Animated Attack are imbued with the souls of unbroken steeds, or of nightmares.
Bag of Devouring
This bag appears to be an ordinary sack. Detection for magical properties makes it seem as if it were a bag of holding. The sack is, however, a lure used by an extradimensional creature—in fact, one of its feeding orifices.
Any substance of animal or vegetable nature is subject to "swallowing" if thrust within the bag. The bag of devouring is 90% likely to ignore any initial intrusion, but any time thereafter that it senses living flesh within (such as if someone reaches into the bag to pull something out), it is 60% likely to close around the offending member and attempt to draw the whole victim in. The bag has a +8 bonus on grapple checks made to pull someone in. [...] Creatures drawn within are consumed in 1 round.
OK, this bag is really good at grappling, and it devours people in 1 round? What if the proposed victim is a better grappler? Instead of automatically devouring an engulfed victim, it must beat the victim in a wrestling match. Otherwise, the extradimensional creature is tamed, and the "victim" climbs out of a brand new bag of holding.
Cloak of Poisonousness
This cloak is usually made of a woolen material, although it can be made of leather. A detect poison spell can reveal the presence of poison impregnated in the cloak’s fabric. The garment can be handled without harm, but as soon as it is actually donned the wearer is killed instantly unless she succeeds on a DC 28 Fortitude save.
A wearer who succeeds on the Fortitude check now has an immunity to this particular poison and gets a nice Cloak of Resistance - and a potential assassination tool. ("You look cold. Take my cloak.")
-2 Sword, Cursed
This longsword performs well against targets in practice, but when used against an opponent in combat, it causes its wielder to take a -2 penalty on attack rolls.
All damage dealt is also reduced by 2 points, but never below a minimum of 1 point of damage on any successful hit. After one week in a character’s possession, the sword always forces that character to employ it rather than another weapon. The sword’s owner automatically draws it and fights with it even when she meant to draw or ready some other weapon. The sword can be gotten rid of only by means of limited wish, wish, or miracle.
-1 and -2 items are tough because they don't force a single moment of conflict; they just make you worse at stuff over a long period. Therefore, you should have to spend a significant amount of time winning the item over. Here are a couple of possibilities.
Armor of Arrow Attraction
Magical analysis indicates that this armor is a normal suit of +3 full plate. However, the armor is cursed. It works normally with regard to melee attacks but actually serves to attract ranged weapons. The wearer takes a -15 penalty to AC against any attack by a ranged weapon. The true nature of the armor does not reveal itself until the character is fired upon in earnest.
I actually think you need to be killed by missile fire in full Borimir fashion, or at least be dropped to the brink of death, to tame this armor. Once you're resurrected or healed, the armor will become normal +3 armor for you. However, if you ever clean your bloodstains from the armor, the curse re-exerts itself.