The user:
search operator lets you limit a search to only posts from a specific user, e.g. user:153020 is:a
finds all my newest answers on MSE.
Often, particularly during moderation tasks it's handy to be able to find posts from multiple users that are prone to the same problematic behaviour.
For example I currently have a set of bookmarks for a "naughty list" that are worth checking up on occasionally, ordered by newest post but for each user with the same rest of the search I have to do it individually. It's easier to see the bigger picture patterns if these are all in the same list.
Please can the user:
operator be expanded to allow limiting a search to posts from multiple users. A possible syntax would be:
user:w,x,y,z
This would also make it possible to write greasemonkey scripts that automatically construct such searches from other pages on the site.
I see the primary utility of this as relating to moderator activities, but certainly not a bad thing to have available more generally.