As a moderator I've found that a nontrivial amount of moderator flags are for posts that are in need of editing and cleaning up. Joel has also recently posted that it would be beneficial for question titles to be complete and grammatically correct.
I suggest that there be a way for any user or anonymous visitor to flag a question or answer as needing editing, perhaps with a short description of what needs to be changed, that other members can then see and edit. Wikipedia uses similar functionality to both indicate to visitors that an article has been flagged as in need of fixing as well as to provide a collection of pre-identified posts that editors can fix without having to scour the entire site for things that need changing. It also allows people that don't have the time, skill, or inclination to actually make the necessary edits to bring it to the attention of people that do.
The way I envision this as being implemented is to add an option under the flag menu for "needs editing" or something to that effect, with maybe a few canned reasons and text box for other reasons. The "very low quality" option from the moderator flag is also moved here. Once flagged, the post then appears either in the edit approval queue or a similar queue visible to any user that can edit. The main purpose of this being to allow the community to be aware of things that need to be fixed instead of just the moderators.