I was mainly thinking of computer RPGs, since I've been playing so much Dragon Age lately. In those games you are limited to two rings, a necklace and a belt. But the world is actually awash in magical items, and you can find yourself at the end of the day with a pocket full of magic rings, but still only able to wear two. I suppose another approach would be the Tolkienesque one, where magic rings are both extremely rare and extremely powerful.