My current build is thus:

Armory is Frostgear of Shadow Council

Glyphs: Howling Blast, Rune Strike, and Death and Decay.

Rotation is: Death and Decay, Howling Blast, horn of winter, blood boil, howling blast, blood boil, blood boil, obliterate, repeat

Tanking macro looks liek thus:

/cast Deathchill
/cast Rune strike
/castsequence reset=combat howling blast, horn of winter, blood boil, howling blast, blood boil,blood boil, obliterate, !death and decay

I also have an exact same macro without deathchill and rune strike, so I can see where in the roatation I am.

Frost strike as a RP dump as necesary.

Holds aggro like nothing else, and typicaly pull 2-3k+ DPS depending on the size of the pull.