An idea I had while dwelling on the Arabian Nights. In the story of Aladdin, a djinni appears every time he rubs the ring or the lamp. My suggestion is:
- the blessed and cursed RoDS keep their current behavior
- if the RoDS is uncursed, when you use it the first time, the djinni appears and the RoDS changes into a new type of ring, the ring of the djinni, which works as a container for your new companion. You use the ring, the djinni appears; use it again, he goes back into the ring. If the ring is destroyed, the djinni becomes hostile. If the djinni dies, the ring becomes a brass ring.
For added flavor, make the djinni spout something when he appears, for example a shortened version of the sentence in the tale (which is "What are thy commands? I am ready to obey thee as thy slave, and the slave of all those that have that ring on their finger; both I and the other slaves of the ring.")

Besides the allusion to the tale, there is another point to this RFE. At the moment, when I find a RoDS, I don't think a second about blessing it. It's true that there are many similar instances in the game, but those are cases of "blessed gives more of the same thing" (think scrolls and potions), while for the RoDS the difference is qualitative, so I feel that the choice between an uncursed and a blessed RoDS should become a real choice, worthy of consideration. If the new behavior of the ring is not enough for this, djinnis could be buffed (I don't know how strong they are now).