The Taverner's Ring of Spell Storing
This silver ring of a serpent eating its own tail holds a maximum of two spells. One is clerical in nature, randomly determined from the levels 1 to 4 spell lists, the other is magic-user in nature, randomly determined from the level 1 to 6 spell lists. Once the spells are determined, they can not be changed.
The ring can be used by all classes, and the magic-user spell contained in the ring can be cast by a user wearing armor.
The spells cast by the ring are gone until recharged. The ring recharges a spell slot (randomly determined if both slots need to be recharged) when a member of the wearer's party dies. Note, the wearer need not cause the death. Henchmen, hirelings and allies do count for the purposes of recharging the ring.
Note, I'll add the OGL to this when I get back to NYC. In the meantime, enjoy ;)