Masks

[Feldherren]

This is an in-house blockhead plugin. It'll be a part of Events. Why? B/c Emp is an asshole.
(Emp's words, not mine.)

If no event name is provided, then it defaults to the player's (admin's) current subscription.

/event mask [event name] [block]
Everyone who is subscribed to this event will show the selected block as their head.

/event mask [event name] drop [on/off]
Default state is disabled. If enabled then players killed will drop one (assuming they're not carrying more on them, in which case it's one more) of the block that is being used as their head for their event.

[Feldherren]

Apparently this is just taking a block and throwing it into the head armour slot.
Might require some thought on how to stop players from being able to remove the block themselves. If this isn't possible, give them a command to replace the block (or rather just put it back on their head, requiring it in their inventory.)

Blockhead plugin code is here: https://github.com/zand/BlockHead/blob/master/src/com/zand/bukkit/blockhead/BlockHead.java so I can study it.