Combat Stats
 

Now, I've probably just missed it here but is there a mod which shows how much damage you and your group have dealt and received after you've just finished engaging a mob?

You'll need an external parser like ACT for that.

Yep, what he just said.

And I highly recommend ACT. Heres a link for ya:

http://home.maine.rr.com/eqaditu/ACT/