In conjunction with edit history provide one or preferably several ways in which interested users can be easily alerted to what has changed possibly in conjunction with a watch-list.

People who have contributed to a jointly authored page, or any page which is editable by others, may have an interest in keeping track of other contributions. The point is that they may have established their own understanding of the page topic or material, and to maintain the effectiveness of this page in their own personal knowledge bank, they need to ensure that no contributions have materially changed the concepts; or if they have, they would want the opportunity either to become familiar with the new material or to make further changes to restore comprehensibility.

This is closely related to the above point about change indications, as it would be helpful for other linked wikis to be alerted when something has changed on a linked page, so that they can in turn alert their owners.

Provided users have an effective ID, it is very easy to allow people to record their interest in any number of individual pages, as Mediawiki does. For some sites, an RSS or Atom feed would be useful, as many people use these to scan for changes that may be of interest. This can work however coarse or fine grained the change record may be.

One feature that I would find very useful would be to alert if any changes I have made are further changed, particularly to material I have authored. This latter would depend on author attribution tracking.

Mediawiki offers registered users the ability to “watch” pages, meaning that every time that page is changed, the user receives an e-mail. Probably several other wiki systems do likewise. But Mediawiki does not (AFAIK) offer any facility for alerts at a finer grain than a whole page.

Some wiki systems (research to be filled in here) offer an RSS or Atom feed of changes, similar to a blog.