The World of Warcraft Armory
14/50/7
I've main tanked everything up to and including sapphiron in 10-man naxx with this without breaking a sweat.
Could almost do Gluth without switching tanks at all; got a little risky after his decimate though
Edit:
I just successfully tanked Kel'thuzad as the sole tank (I tanked the two adds as well).
I have the emblem trinket (9% dodge for 20 seconds) and I was able to pretty much keep one cooldown or another up for the entire duration of the third phase. I did get some bursts once in a while but I did not feel that I was at any time close to death
