As far as cursed items go, there's nothing quite as boring as a "sword -1". Here's the great treasure of the Painted Men, which bears a much more interesting curse. If sold at the Bazaar Incomparable, much like the Malicious Mirror, its new owner will be seeking the party out - so it's an adventure hook as well.
The effigy is a 1’ tall statuette of a clown, carved from ivory with jade inlaid in a checkerboard pattern. The statue is worth 700 gp to a collector of fine art, assuming said collector is unaware of its curse.
Anyone possessing the statuette for more than a few hours will begin hearing circus music in the distance. Over the next week, the music will come closer and closer, until it sounds like it is in the next room – at this time, the harlequin spirit will appear.
The spirit appears as a faceless clown, and is visible only to the owner of the effigy. The spirit will torment the viewer day and night, even appearing in the owner’s dreams.
During the second week since the statuette was acquired, the spirit will stay on the periphery of its victim’s vision, sneaking around, rifling through his belongings, and so forth.
During the third week it will appear with knives, cleavers, and instruments of torture, getting ever closer and making threatening gestures at both the victim and his associates.
Beginning in the fourth week, the victim’s associates will be murdered in bizarre circumstances. Oversized bloody shoe-prints will be found at the crime scenes, and swatches of bloody green-and-white motley may be found clutched in the corpses’ hands. If held by a party member, other player characters should never be murdered this way - henchmen, innkeepers, and other NPC's are all fair game, however.
If the curse has not been lifted after the fourth week, the spirit will kill its victim.
Prior to the spirit appearing, transferring the effigy to someone else is sufficient to end the curse. Once the spirit has appeared, however, disposing of the statuette is no longer sufficient – the harlequin visions will continue on their murderous course until the curse is broken or the victim is dead.
The sacrifice of a clown (or painted man) before the effigy will sate the harlequin spirit’s need for blood. The effigy’s cycle of bloodshed and murder will be effectively “reset”, and in a week’s time will begin anew with circus music being heard again by its owner.
Remove curse will not dissuade the spirit - only the death of a clown is sufficient.