I believe we should hold elections, where we solicit nominees and vote as per the standard upvote/downvote mechanism on the site.
The post will be marked community wiki, so that votes will not impact a individual's reputation.
Nominations would look roughly like this:
I, John Q. Public, nominate myself as a Ubuntu Stack Exchange moderator.
I is uniquely qualified for the position because I have done X. If elected, I will promote freedom, justice, and the Ubuntu way.