The ideas are simple: a way to identify, in a raid frame, which of the raid members are close enough to throw heals on. The issue is that in PvP, especially in places like AV, targeting becomes difficult (that gnome needs to stop JUMPING AROUND!) and that makes it much more difficult to heal. If a raid frame simply changed color or had a border when that target was in range, clicking it and healing would be much less chaotic.
Another idea would be to take the "Proximo" (arena frame) idea and extend it to identify, after a reset and via a mouseover, those targets in the vicinity. The healer would have to pretty consistently update it, but it would be up to that healer to do so. Have a toggle such that it either targets friendlies (for heals, cleanses, etc) or bad guys (like Proximo, but not limited to arenas).