Useful Drupal modules

Click on the module name for notes, comments, patches.
Recommendations (for and against) are my personal opinion only and may be out of date. Feel free to email with corrections/suggestions.

Why haven't you mentioned Drupal 9? I will be adding this, but as of August 2021, this site you are reading is the only Drupal site of mine I've been able to upgrade to D9, so although you can check D9 compatibility status of all modules (use upgrade_status, it's superb) I can't speak from personal experience about any of them.

(1 modules in list)
Module name or machine name
Any text in the notes
Name D8 Personally Tested Last Updated
Role Watchdog (role_watchdog) 2018-11-20

d.o. page

Logs every time a role is changed. Users get a Role History tab and there's a notification feature. 

Not ready for Drupal 8 yet (15 Sep 2018 - there's a dev branch, but when you install it complains about missing role entity, and drush updb does nothing)