On Stack Exchange, sites have "Review queues" for users with enough reputation points to review certain posts.
For example, this is Maths Overflow's review queue.
There are 6 different review queues.
First Posts: Whenever a new user posts his first post, his post appears in this review queue/. This could be a question, or an answer. Available to anyone with at least 500 reputation points.
Late Answers: Whenever a new user posts his first answer to a really old question, his answer comes in this review queue. Available to anyone with at least 500 reputation points.
Suggested Edits: When a user with less than 2000 reputation points suggests an edit to any post, the suggested edit comes under this review queue. Available to anyone with at least 2000 reputation points. If the edit is approved, the suggester gains 2 reputation points. If it is rejected, nothing happenns.
Low Quality Posts. When an ordinary user flags a post as "Low Quality", the post appears here. Ava4ilable to anyone with at least 2000 reputation points.
Close Votes. When a user with at least 3000 reputation votes to close a question, or when a user with less than 3000 reputation flags a question, this question appears right here for review for users to vote to close or leave it open the question. Available to anyone with at least 3000 reputation points. If at least 5 users vote to close the question, it will get closed.
Reopen Votes. Similar to Close Votes, but for reopening questions instead. Available to anyone with at least 3000 reputation points.
Now, in my opinion, the "First Posts", "Late Answers", queues are not necessary.
The "Low Quality Posts", "Close Votes", and "Reopen Votes" review queues are not so necessary either, since it is possible to use a meta thread where users can ask for closing/reoepening of questions, and other users can vote on that.
That boils down to suggesting edits. This is very important for community moderation. Is there any Q2A plug-in for suggesting edits, and suggested edit review queues?