5.000.000+/- during a 11min+/- SotA match on my hunter..
I never had any AV Turtles/reinforcement battles on any of dps chars at 85. The last time I had one of these AV's, it was on my lvl 48 boomkin who did like 140k+ damage.
9.000.000 healing done in a AV reinforcement battle on my lvl 85 Pala at the start of cata(in my leveling greens/blue's).
Ye.. not as impressive as the others listed here.