The formula I propose for this is a point system, where the points add up for various achievements. If you earn 10 points or over, you are automatically considered a stakeholder; a person with a legitimate stake in the Mana World, that could vote, if appropriate. It goes as follows:
+10 You are, or have been, a GM, Developer, or Admin in TMW.
+1 For every year with the project. You can use either your forum account age, or your player account age.
+1 For every sword next to your name as a regular user on the forum, to denote activity on our officlal forums. I believe the maximum is +4 or +5.
+1 For every 2 levels past 89 on your highest level character only. This should amount to a maximum of +5 at level 99.
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I've been here a while, actively participated in forum discussions, and I've worked on my character in game also, so I decided to test it out on me, for fun:
+0 I've never been a GM, Dev, or Admin.
+5 I've been here for 2007, 2008, 2009, 2012, and 2013. I am excluding 2010 and 2011, because I was not active then, although that would rely on the honour system, and in practice, it would be hard to know this automatically for a machine generated list. Still, we could make the applications as requests on the forums, instead of machine automated, if that sounds more appealing. (Sounds like more work to me ...

+1 For forum participation. I'm a one-sworded Peon with about 96 (97 after this one) posts.
+2 For character levels in game. My main, Selenil, is level 93.
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Well, I'm at 8 points. Still 2 more points to go in order to reach 10 points. I could post some more (but not spam, of course), or level my character higher. Of course, I could get into development too, although I have some fears about that, which is a personal obstacle I would have to overcome. I feel as if I've already put a lot of effort and love into TMW, but still not enough, even by my own suggested metrics. And that is perhaps a good thing, because even if it becomes possible one day for long-time contributing players to have a say (without going the dev / GM route), it should be neither fast nor easy, I guess. Sort of like an earned citizenship in ancient Rome, perhaps.