I have, I don't know how it would work in SMP though.
Well, the thing is that it would work in smp just like it would in singleplayer, the effects are instantaneous, you wouldn't need to actually "sleep" BUT as you can see you can only things a limited amount of times everyday, and you can't stack effects from other kinds of resting.
Section: Wasteland Mobs
Subsection: Ghosts and the Undead
Description: They used to humans, but they were exposed to too much radiation, that caused genetic mutations and cancerous growth, that, instead of killing them, caused then be become somewhat immortal. Having wandered the wastelands for their entire life, they were exposed to so much radiation until their bodies were mutated beyond recognition, and their figures were distorted and horrid. After a decade of exposure, they have lost the ability to speak. Although they do not age, they have to sustain themselves via hunting and eating human flesh. They no longer have the minds of sentient beings, but have savage and wild instincts, that drive them to kill, kill, KILL!
They are 2x2x3 mobs that are aggressive. They look somewhat muscular, but have a rather big right arm, and their heads are attached to their left shoulder. They have 3 types of attacks, the first being a jump attack, where the Abomination jumps into the air, and when it lands, it causes a small explosion (doesn't hurt itself though). The second type of attack is the charge attack, where the Abomination charges at the player, and rams into him, causing a 3-5 block knock-back. The last attack is a throw attack, where the abomination picks am a block with its massive right hand, and throws it at you. they block causes mobs around it (passive or hostile) to get damaged, and causes them to be unable to move for 1 second.
I don't know if you want human factions, but here is my idea anyway.
Name: Twisted Religions (Can be changed. Even I don't really like the name.)
Section: Wasteland Mobs
Subsection: Human Factions
Description: These people are a standard human faction, living in towns, settlements, or lone camps, but their defining feature is their bizarre religious practices. Based off government propaganda and corporate advertising from a pre-wasteland era, they worship dead political figures and company mascots, as well as altering and misinterpreting existing religious practices to the extremes.
The easiest way to identify these groups is to find a shrine in the villages, most likely a rock, decorated with old posters and drawings of their pagan idols. Another identifying these people is every so often they will perfome an odd ritual, which only makes sense to them
If you come across objects considered sacred to them, they will pay heavily to have sacred artefacts returned to them.
^ ^ yeah I thought we had some factions or something going on earlier, but idk what happened to it.
AFAIK what happened was that they had a pretty complete concept, then people started making a ton of suggestions, until one day i made a gigantic suggestion, Lemon said he liked it and he'd work on it ASAP, and nothing was posted about NPC's ever scince, maybe they're working on that secretly, maybe they left it for later when they started working on the "easy" things right after world generation.