I thought I might share some of the research I've done on easily available gear at 80 so that we can get all of our tanks up to heroic level as quickly as possible.
I look at three things when choosing gear: Defense Rating, Stamina, Dodge/Parry/Block and finally Strength. Hit may be import for warriors, but it should be a distant 5th attribute to look at.
Your first priority should be getting Defense to 540. This will make you uncrittable to raid boss mobs. It's best to get overlapped at first, that way you can upgrade gear and still have some wiggleroom with your defense.
Stamina x 10 = HP. Nuff said.
Dodge/Parry/Block gives you more effective HP. Work on these too.
Strength x 10 = damage blocked from a shield block. (I think this is right)
Anywho gear:
-- CRAFTED ITEMS --
Tempered Saronite Set:
http://www.wowhead.com/?search=tempered+saroniteThis set is awesome. This will get you overlapped on defenses and ready to go at 80.
-- REP REWARDS --
Put on your Wyrmrest Accord tabard and don't take it off until you hit Revered. These three things are very nice:
Cloak of Peaceful Resolutions
http://www.wowhead.com/?item=44188Breastplate of the Solemn Council
http://www.wowhead.com/?item=44198The best pre Naxx chest piece. GET IT!
Sabatons of Draconic Vigor
http://www.wowhead.com/?item=44201Defense, Hit Rating, Lots of stamina. Better than a lot of crafted purples.
After the Wyrmrest Accord, the Argent Crusade should be your next faction to gain rep with.
Special Issue Legplates
http://www.wowhead.com/?item=44240Gobs of defense, hit, stamina and a socket! And only requires honored. Easy to get.
Arcanum of the Stalwart Protector
http://www.wowhead.com/?item=44150This is -the- tanking head enchant. Kind of a pain since you need Exalted, but you will need this down the road.
Knights of the Ebon Blade only has one piece of gear for tanks really.
Toxin-Tempered Sabatons
http://www.wowhead.com/?item=44243These are an alternative to the boots of Draconic Vigor. These have a little bit different itemization with block value. Still pretty good, but requires honored. There's a drop in Culling of Strath that is identical to these though.
-- QUESTS --
Do the quest, Wanted: Ragemane's Flipper. For the Hammer of Quiet Mourning. It's fast, has fantastic defense and dodge. The axe might have more defense, but it's too slow for tanking. Faster weapon = more rage/more seal of corruption stacks.
http://www.wowhead.com/?quest=12857Alternately, you can do Tirion's Gambit for the Sword of the Empty Void. It's not as good as the hammer, and requires more prerequisites, while Ragemane's Flipper takes about 5 minutes. Still, it's an option:
http://www.wowhead.com/?quest=13364Do the quest, Halls of Stone. Very easy quest that you can complete by just doing a run through on normal mode. The Pauldrons of Reconnaissance are very, very good.
http://www.wowhead.com/?quest=13207For Prosterity requires a run through of Gun'drak. Very nice ring reward:
http://www.wowhead.com/?quest=13098Long questline in Scholanzar Basin ends with A Hero's Burden. Rewards the Blood Infused Pendant, which is awesome.
http://www.wowhead.com/?item=39485-- NORMAL DUNGEON DROPS --
Halls of Lightning:
Seal of the Pantheon
http://www.wowhead.com/?item=36993Gun'drak:
Gal'darah's Signet
http://www.wowhead.com/?item=43306The Oculus:
Dragonflight Great-Ring
http://www.wowhead.com/?item=36961I'll append more if I find it.