I propose a community initiative to edit through the tag wikis (and of course, approve them) during a two-three days period, perhaps some weekend in the near future.
The idea is that we agree on a weekend, and everyone who is willing to partake will specify which tags he is even able to edit (I, for example, am unlikely to edit anything related to categories - while probably competent enough to write something for axiom-of-choice (oh right, I already did that :-)))
Then we set to write, updating on this (or some other?) thread on the meta so that the high-enough rep. users (and moderators of course) could approve, and others could edit and so on.
We could work a general guideline for writing tag wikis, or use the ones that are written as example (choosing those which are properly written as a study case, and fixing the others).
Perhaps for that period of time the rep. limit for editing tag wikis can be lowered to a reasonable limit of 3-4k to ease the work load on the moderators and trusted users as well?