WhatsYourDamage displays the calculated damage or healing of abilities with talents, gear and buffs included on your actionbar buttons. The addon also adds various statistics to the tooltips in your spellbook and on the actionbar.
This intended to carry on after the now defunct DrDamage. Note, this is not currently functioning, I'm working (albeit slowly) on this. Folks who wish to contribute/develop, please send me a PM and I will work with you.
This is intended to be a new iteration...