If you’ve ever created a quiz form and need to add new questions, it can be difficult to quickly identify questions in the item categories that are appropriate and not yet used in a quiz. This local plugin by Ray Morris provides an easy way to identify whether you are looking at potential questions which have or have not been added to the quiz already. (Another improvement would be a warning from Moodle if a given quiz includes a duplicate item by item ID.)
The plugin is available for Moodle 2.7 and 2.8, check it out here: https://moodle.org/plugins/view/local_unusedquestions
This could be a real time saver for teachers and course developers. If you’re interested in this, I’d encourage you to check out the Quickfind List (for searching users) and Search Questions (search the question bank) which are both plugins that could make Moodle that much easier to use.