i saw this plugin called runecraft or something like that that has a lot of different features depending on how you place cretin blocks, but i don't really care about most of them except the hidden doors, here are a couple of videos demonstrating how they work,
idea is to basically rip off the hidden doors part of this plugin and make it part of innectis XD. also a page on the minecraft wiki explaining how they work:
http://www.minecraftwiki.net/wiki/Runecraft#Hidden_Door there are loads of different uses for this plugin and i know hret had talked about adding something similar i think, but if they could just pull apart the code of this plugin and reuse that it should take some work off of them.