Would it be possible to program a mob to randomly cause blocks within a certain vicinity of it to pulse with a redstone signal?
If so this could make a truly amusing and scary mob. When they get close the doors of the house would start randomly opening and closing, any redstone machinery would act wonky, and any lamps would start flashing. All things we see in scary movies and such, and yet not very destructive...unless you keep TNT placed around your house I suppose. Also it might allow other mobs to have an easier time entering your house if for example it pulses a door open and zombies were near it.
A mob like this would be possible, but very laggy. When it would pulse that redstone signal all around it, this would cause quite a bit of load all at once as it checks each block around it to see if a redstone current can affect it. It would be like turning on and off 20 redstone torches at the same time a bunch of times... hello memory leaks.