Just a thread for theorizing about what the rings that every Akatsuki member wear does.
Facts about them are as follow, they're obviously very important, since without them a new member cannot be inducted into Akatsuki, they also seem to be irreplaceable since there is still only nine members years after Orochimaru had left the organization. They are also placed on finger that the particular member belongs to on the statue. The kanji on each ring are unique and they often represent constellations or other mythological entities and concepts, the specific character and their meanings can be found here.
Inferences that I've made are as follows:
They seem tied to a specific person's body, when Sasori switched bodies, all articles of clothing were left on the previous puppet, though his face, eyes and heart talisman were transported, the only visible non-organic item that was also transported was the ring.
They may be used for communication, this is seen when the AL speaks to Hidan and Kakuzu. If he can target this at everyone, it would be safe to assume that he already has god-like powers, anyone can be driven insane by his voice in their head, no matter where they are.
They may be used in the sealing ceremony and other gatherings, this follows the same logic as the for communication via the rings, each ring is tied to a finger on the statue, and without a ring an applicant cannot become a member, it also follows that not everyone will be capable of learning what seems to be a rather complex jutsu in a very short period of time (Tobi was sealing biju just days after becoming a member and Hidan still didn't know what Akatsuki's goals were).
They may act as a form of duress for the lower members, this can be seen by the fact that Deidara was more concerned with recovering his ring than with recovering his arm, and Hidan suddenly stopped arguing with the AL despite the fact that he hadn't completed his ceremony. This argument isn't very strong, but there has to be a reason that everyone obeys the AL without him showing any outwards signs of aggression. This assumes that after putting the ring on, going without it for long periods of time will result in death or incapacitation in some other manner.
Any other thoughts about this?