[SUGGESTION] func_shooter or something like it

Just think about it: Equip your map with rocket cannons and grenade launchers, to be triggered with just anything.

Recommended key-pairs:

type : "rockets", "grenades", "electro" (electro: a 1 sec burst)
target : [target_position or info_notnull, where to shoot at]
targetname : [shooter can be activated by a trigger]
repeat : "-1" (forever), "0" (no repeat), [int]
wait : [float] (how long between shots; no less than 0.25)
wait_rnd : [float] (random variation to wait)(optional)
message : [string] "=(Message displayed when player gets fragged by this. Default would be "World was cruel to #"

Bitflags:
TOGGLE (triggering toggles the firing)

So the shooter would shoot like selected weapon at the target_position or info_notnull which it targets.

So............................................... Turrets?