I was farming reputation with the Sunreavers and so Horde Expedition. I remembered heroic LK dungeons grant rep with all those factions but they are limited to a once-a-day. I know, you can repeat them in normal mode, but they give much less rep in that mode.
So, I was killing Jedoga Shadowseeker in Ahn'kahet: The Old Kingdom and realized the adds that spawn during the fight grant 25 rep with Horde Expedition (or Alliance Vanguard if you play on the alliance) and half of that with the Sunreavers (or Silver Covenant if you are alliance), The Hand of Vengeance, Warsong Offensive and the Taunka. And if you reset the encounter they will respawn during the fight and will give rep again.
In order to do this you need to start the encounter by pulling the Twillight Initiates.
Then you can kill the adds who grant rep, the Twillight Worshippers in spot A and/or B:
After killing them you only need to take the boss to any of those 2 spots and the fight will reset.
It takes around 20-25 secs to do the whole process and you will receive around 250 rep with Horde Exp/Alliance Vanguard (and half of that with the sub factions asociated with those).
Horde expedition and Alliance Vanguard are useful for engineers, they sell the Chopper Pattern and other useful stuff. And the Sunreavers and Silver Covenant at exalted grant you extra quests at the Argent Tournament, that means more Champion's Seals and faster mount farming.
Have fun :gusta: