Not sure if this has been suggested before.
I think that it would be nice to know when I hit things. There have been too many times when I have fired clips at people without knowing of a hit. It would also help with throwing grenades as in showing if you actually did damage to somebody.
It would be a little marker or markers just outside the aiming reticule. It would come up when you hit things and not at all be there when you are not attacking something.
I am not trying to make blockland Call Of Duty. Please don't bitch about it.