Weekdays is a lightweight plugin that adds 8 customizable days to your server, based on the different moon phases already present in the game. It aims to add a greater sense of passing time to your server, and will eventually include different configurations and/or hooks to add customizable events and flavor to each day (days without weather, days without mobs spawning, etc).
The names of days and any effects I add will be fully customizable per-world, and I may eventually add ways to reduce the number of days from 8 (in the form of skipping in-game days entirely) to make it more flexible.
I am also considering adding ways to change time scaling (modifying the length of days/nights) in lieu of properTime if that plugin falls inactive.
I'm still flushing this out and will do a release when I've modified it enough to be usable on servers other than my own. Any feedback is appreciated.