I added most of my Wikipedia user scripts to this GitHub to make pull requests/collaboration easier.
Keep in mind that the versions on Wikipedia may be slightly more up-to-date.
User scripts in folders tend to contain some or all of the following:
I like unit tests. Lots of Wikipedia user scripts can be broken into true functions that input 1 string (wikicode) and output 1 string (wikicode). So they are a perfect fit for unit tests. Userscripts with a lot of unit tests include GANReviewTool, DraftCleaner, and SpeciesHelper.