reputation can be gained by purchasing the Tabard of the Argent
Crusade from Veteran Crusader Aliocha Segard in the Argent Vanguard.
While wearing this tabard in level 80 dungeons will award 2 to 30
reputation per mob kill depending on difficulty and roughly 300
reputation per boss kill.
can also gain reputation by visiting the Argent Tournament in
Icecrown. You should be able to gain roughly 1350 reputation just doing
the quest line to open up the Championship Level, and a possible 1100
reputation with the new dailies. Once you reach a high enough rank
there will be six daily quests available:
 A Champion Rises
 Taking Battle to the Enemy
 Among the Champions
 Battle Before the Ciradel
 Threat From Above
 Contributin’ To The Cause
note that all these quests except for Contributin’ to
the Cause will give Death Knights, Knights of the Ebon Blade reputation
instead of Argent Crusade.
for the Argent Crusade can be purchased as you gain faction
from Veteran Crusader Aliocha Segard located in the Argent Vanguard.
of the Argent Crusade]
of the Fleeing Shadow]
of Holy Extermination]
of the Stalwart Protector]
Guardian’s Twilight Opal]
of the Neverending Path]
of Purified Thoughts]
of Hopeful Light]