My guild is currently 4/6 in SSC (Leo/Vashj to go), 2/4 in TK (Al'ar/KT to go), 4 down in ZA, Gruul/Mags on farm, run 1-2 groups in Kara weekly for badge farming.
I tank HKM, Gruul, Mag, Lurker, Hydross (in NR gear, of course), FLK, and Leo (so far).
My main gear for progression tanking is shown currently. My typical swap-slots based on the encounter are:
Legs, from Wrynn to T4 for more mitigation
Hands, from Maidens to T4 for more mitigation
2nd trinket, from Pocket Watch to Spyglass*
Shield, SSO to NB's as needed (very seldom)
*Typically, I've been using Spyglass on all fights except bosses; my TPS stays in the 800-1000 range even on trash using this gear.
The +4 DEF / +6 STA gem in the helm is there only because before I re-specced out of Imp Def Stance (and traded NB shield for SSO which has no DEF rating), I didn't have Anticipation. Looks like I need to re-gem that socket for +12 stam.
Then again, when I get the Bonefists, I'll lose 7 DEF and need to gain 1 more DEF to be at 490 (this is the main reason I don't have them yet, aside from needing ~14 more badges).
Wait... Bonefists plus just (1) +12 STAM gem is the same HP as Maiden, put a +4 DEF / +6 STA and I am ahead of where I was before. Hell, I'm critiquing myself as I go
I have Sun-Eater, rarely used except for heavy avoidance fights (Morogrim, but I almost always have a feral tank him anwyay, though I have successfully done it).
I can't get Mallet of the Tides to drop Maybe this week...