As discussed in this thread, I think a list.ForEach([proc]) function would be super neat and useful. Not a priority, but it would certainly be nifty.
var/list/MonsterList = newlist(/mob/monster1, /mob/monster2)
MonsterList.ForEach( Kill() )
Ex. ForEach() would be a proc for lists that would go through everything in the list and call the proc supplied in the [proc] argument. This would effectively "kill" all the monsters in MonsterList
A built-in proc like this pretty much calls for anonymous functions and a bunch of other features from functional languages.