While leveling, you don't technically need a ton of defense unless you are running a lot of instances. If you are, then you should pay at least some attention to defense. Once you hit 80 you should have 540 defense rating (the number required to be uncrittable). This isn't too tough just from buying crafted blues off of the AH.
Starting at about level 74, you can use at least some of the Tempered Saronite armor set pieces, which all have +Str, +Stam, and a load of defense. At 78, you can get things like
http://wow.allakhazam.com/db/item.html?witem=41357;source=live and
http://wow.allakhazam.com/db/item.html?witem=41345;source=live which will add even more defense compared to the tempered saronite pieces.
At your level, doing the Nexus (and the 4 quests you get for the Nexus in Coldarra) if you haven't done so already will get you gloves, shoulders, and one other tanking piece as quest rewards (necklace maybe? I forget).
There are also quests available for tanking weapons, rings, and an really nice necklace from A Hero's Burden (quest in Sholazar Basin).
With just crafted blues from the AH and some quest rewards, you should have enough true tanking equipment before you even get to level 79 to have 679 defense rating and a ton of stamina. You may need an eternal belt buckle and a few defensive glyphs/enchants to get it there, but it isn't too hard to do. If I have some time, I may put together a list of some of the easier stuff to get, but I am kinda hoping that Losie puts together a gearing guide for tanks for WotLK so I don't have to put my list together and can just contribute to his instead :)
Here is a link to my armory to see what I have at 79. What I have is adequate to do a fair number of Heroics already once I hit 80. My stamina should be a little higher, but it will be a lot higher once I hit 80. I already have
http://wow.allakhazam.com/db/item.html?witem=42508;source=live and
http://wow.allakhazam.com/db/item.html?witem=41392;source=live waiting for me in the bank for when I hit 80.
Don't forget that you can still go get the shoulder glyph from Aldor/Scryers and the head glyph from KoT on your WotLK equipment until you get the rep for the better LK ones.
http://www.wowarmory.com/character-sheet.xml?r=Emerald+Dream&n=Arthang One of my rings is a quest reward from Sholazar Basin, the other is a quest reward from Drak'Tharon keep, the necklace is from "A Hero's Burden" quest in Sholazar Basin, and almost all of the other stuff is crafted (I am a BS so I made it myself, but all of it can be purchased from the AH for reasonable prices). The one exception is my sword, which is still from Heroic Mech, but there are several quest reward options in LK for tanking swords or maces that were discussed in another thread.
EDIT FEST: My cloak is still from Kara, but there is a better cloak available for Honored with Wyrmrest Accord. My breastplate is a rep reward for Honored with Kalu'ak.
Edited, Dec 5th 2008 1:58pm by jeromesimina Edited, Dec 5th 2008 2:00pm by jeromesimina