If you can get a group, be sure to do the
Durn the Hungerer quest before you leave Nagrand. You'll get a solid tanking weapon for a reward.
Another Nagrand group quest,
Forge Camp: Annihilated, gives you an amazing tanking chestpiece.
Check out Xordon's FAQ at the top of the forum - the gear lists in there will help you figure out where to go next and where to get some solid tanking gear for your prot self :)
Cheers,
Jorge