Hi Aaron! This one should be pretty straightforward.
This module lets the user specify a "flatfile" (CSV) containing enrolment information. On a regular cron cycle, the file is parsed and then deleted. The expectation is that some external process will be regularly dumping updates in this location.
Look at enrol/database for a good example of the required structure, and the old enrol/flatfile for the logic.
Note these rules for plugin file names:
lib.php - the main class (interface)
locallib.php - any local internal functions never to be used outside of your module
settings.php - all the settings, to appear in the admin menus in the settings block