Even though the Margiela knuckle duster (above) I got myself (and my sister-in-law, bought the last two in the shop) for Christmas is super comfortable to wear, it doesn't make typing very easy. When I discovered these Made Her Think rings online, they pleased me to no end. They fulfill the multi-ring effect but without constricting your hand span, because they're attached by chains instead of fused together. Only problem is that they're a few hundred USDs, money I can't be spending on buying rings online due to my inhumanly small fingers which only work with adjustable-size rings. (The smallest size at F21 is big even on my thumb.)
That said, anyone with normal-sized fingers would go ga-ga over these, and a lot of the collection is actually a lot more reasonable in price. You can get rings for around US$60, going all the way up to US$2000+. Hm.