In the normal PlayerFrame, you see when someone hit you and for how much, if they miss, you dodge, what you got healed for etc. But this is not present for the TargetFrame (or TargetTargetFrame addons) and only addon i know of only adds what damage you do to the target, i'd really like to see an addon be developed that adds these texts to the TargetFrame, or possibly also the custom made TargetTargetFrames. This doesn't necessarily need to be a n ACE addon, but I suppose this would save resources.
AceCombatHUD does this. It places two circulare bars going around the portaits, ie yours and your targets and adds the combat spam to them along with showing each's health, mana etc. Note however that not only your damage is displayed but all damage done to the target.
yes, that is just fine that it shows everything, but it doesnt add it to the TargetFrame itself, it creates own portraits (atleast the version i tried out) and i dont really wanna bloat my screen more then necessary (no doubt combathud is nice, but thats not what im searching for right now)