• Dawn's Reach, which can be found in the far east part of Dragonblight.
• Light's Breach, which can be found in the center of Zul'drak.
• The Argent Stand, also to be found in the center of Zul'drak.
• The Argent Vanguard, which can be found on the southern part of the Icecrown Glacier.

There are many quests that give reputation with the Argent Crusade faction and you can also buy the Tabard of the Argent Crusade from their Quartermaster once you get the Friendly status with the Argent Crusade. You can wear this Tabard in any level 80 dungeon to receive reputation for each mob that you kill inside the instance.

There is one trick to get thousands of reputation points with the Argent Crusade in no-time. There is a quest in Zul’drak called Pa’Troll. This quest can be taken at The Argent Stand. This quest will give you 4 objectives and you can complete one of them for 250 reputation, without handing in the quest. You can then remove the quest Pa’Troll from your quest log and take it again at The Argent Stand.

Now it makes sense that you will complete the easiest of the 4 objectives which is the following one: Lab Work. This part of the quest requires you to search four materials in a lab and take them back to the quest giver.

Lab Work:

‘Alchemist Finklestein at Heb'Valok wants you to find a Muddy Mire Maggot, a Withered Batwing, an Amberseed, and some Chilled Serpent Mucus from within his laboratory.’

The lab is right behind the quest giver, so this quest is really easy and will only take a minute of your time. After you complete this part you get 250 reputation and you should delete the quest from your quest log. Take it again at the Argent Stand and complete this quest again and again.

All together it is not more than 2 minutes work for 250 reputation which equals to 7500-10000 reputation per hour. It might not be the most fun way, but definitely the most efficient one. Imagine yourself doing this one hour per day and reaching exalted status within 4 days (excluding all other reputation gains from instances, other quests etc.).

Next to the 250 reputation you will also receive 6 gold per turn in and 2100 XP (which is also converted to gold if the player is 80). Doing this quest 30 times (1 hour) would not only mean that you would receive a lot of reputation, it would also mean that you get 180 gold and 63000 XP. Not bad for an hours work.