I was looking at all the discipline priests talk about the lack of AoE healing to the spec. I do think that disc does lack some sort of aoe feature but I don't think it should be as raid effective as the other classes. A new ability entirely would seem to tacky and bulky for the class, so I was thinking this:
Inner focus - Empowers your next penance spell increasing the healing done by each hit by 100% but is split between 3 targets (I would see this ability working like chain heal. 3 targets closest, lowest health first, followed by 2nd lowest, etc.)
Whatcha think mmO?