Public wiki

A public wiki is any open for anyone to edit, including those used to gather public input (by governments, NGOs, etc.):

Facilitate the use of the wiki by focusing attention of specific items/topics/draft documents for a specific amount of time.
Provide optional content templates for new pages - like user pages for particular types of people you want to encourage to contribute, e.g. expert users in some topic
Start with some substance to encourage substantive edits, don't expect most users to start from nothing - otherwise the most motivated extremes will start with polarizing content; includes example of good starting material.
Obscure the fact that a very few people are creating a large amount of material at the start, so that others are not intimidated - chalk it up to anonymous trolls and beg for better content so the wiki is not taken over by trolls
Use mediawiki - more people know it than any other, it notifies everyone of changes well enough, and has extensions that help limit wiki spam
Get topic names right from day one, and correct errors with minimal comment
Keep the wiki troll-friendly by forbidding administrators to avoid speculation on undeclared identity or engage in ad hominem deletes, and respecting new troll point of view
Obey other wiki conventions and wiki best practices and evolving praxis that your users think is important, especially with regard to controversy, e.g. trolling.

A large public wiki has special problems and issues and the latter factors matter more.