As of 4.0.0 Alpha 1, there will be a Special:MostContributions, which sorts and displays users who've contributed to the wiki, with those with the most displayed first. Additionally, you can filter MostContributions with a pageid or target, to show the users and their edit counts that are only relevant for the specified page. Also, the list of contributors below the article will now show each user's total contributions in parentheses.
Originally requested for 3.0.14.