Amulet of Anti-Magic: absorbs a fixed amount of damage to that minion from magical sources per fight
Amulet of Arcane Power: increase in DD caster level, but only verses AMF, damage does not increase. (I've wanted this item for almost as long as I've played, mostly tried to sell it as a Ring of Power previously)
Amulet of Accuracy: PTh bonus, max similar to AoAC
Amulet of Retribution: Adds to weapon or spell damage, but only in rounds where the wearer takes damage from Melee weapons, and only to the person who dealt the wearer damage.