PostEdit

PostEdit is a simple extension that shows a brief popup window that says "Your edit has been saved" after you submit an edit.

It's not "needed" by any means, but it can be useful to verify your edit was duly logged and recorded by the database that stores all the information for your MediaWiki setup.

'''Note: This extension is obsolete in MediaWiki 1.22 onward, as its features are incorporated into the MediaWiki core".