This tool allows you to pick a category of media on the Wikimedia Commons, and a source and target Wikipedia language, and yields a list of articles in the target language that do not yet include media items in the selected category that are included by the same articles in the source language.
In other words, it allows a wiki to follow the lead of another wiki in integrating media in articles, and saves the user tedious clicking around to find applicable articles and suitable media. Particularly useful in smaller wikis and/or facing large media categories (e.g. "GLAM" media donations).
To see it running, go to https://meta.wikimedia.org/wiki/User:Ijon/GLAMify