A plugin that makes nether portals unable to be lit up by flint and tinder, and open only for a thirty second window when the portal is outside and while the moon is directly above in the sky.
This sounds interesting...I think you'd have to do it by keeping track of the world's time somehow. I'll watch this thread, and post back if no progress is made for awhile.
Given that nether isn't supported, it is probably best to ask for that in the thread of the particular nether portal system plugin you are using.
