It would be nice if (at least) for pages on the watch list, MediaWiki would
store per-user information about what specific version this user last saw.
Update of this information might happen if the user specifically requests it,
and not every time he visits that page.
This would make possible a new kind of watch list view: sorted by the number of
times that page has been updated since the user last inspected it.
There should be a link on that watchlist page which shows the diff between the
stored version number and the current version that at the same time updates the
information in the database (see paragraph 2).
This would make the watchlist much more useful.
For privacy reasons, each user should have to explicitly activate that feature,
because the information which version of a page (and thus, when) he visited is
sensitive personal information.
This depends on bug #181 because the ID of the current version needs to be stored.