I'm not eligible yet to create one, but will be soon, and I'm very interested in contributing to the community in addition of answering questions.
What is meta?
- Any Stack Exchange user can ask a question
- The community provides support, votes on ideas, and reports bugs
- Your voice helps shape the way Stack Exchange operates
A pretty roughly formatted list lives here: http://stackoverflow.com/tags/tag-wikis
It's a bit complicated, because in some circumstances it's possible to have orphaned tag wikis that don't correspond to any valid tag. See http://meta.stackexchange.com/a/114184. The list of these is apparently only available to moderators.