I have Onyxia on my "to-do" list. Granted I only have the 2 shamans right now but they are lvl 66, and I have a dwarf priest lvl 66, I am thinking of getting another account and transfer him to it so I can use him with my shammies. I think when I hit 70 and get the proper gear i could do it.
More than likely need my friend to tank tho.