That is an epic idea there!
Whoops, forgot the format.
Add-On Name: (Undetermined) LE Grenade, Fragmentation grenade, Bushi-nade?
What it would do: A one use item that the player could carry multiple of, not unlike the HE Grenade. Timer starts when thrown. when timer runs out, the projectile releases several small shrapnel projectiles that have a short existence, but a somewhat large damage to compensate. (Maybe some visual explosion-ness?) Throw in sounds n' such and you have a grenade that is perfect for blowing up the in-doorsy types.
Screenshots and other conceptual art:
_O'_
/+++l
l++++l < grenade
\+++ /
Except not crap.
=]