One of the most efficient ways to earn reputation with any faction is to do their associated daily quests. If you can develop an efficient system of picking them up and doing them in the proper order, you can earn all the reputation you need with minimal effort. Having a good plan for doing reputation dailies is especially important if you are working on more than one faction at a time.
Using the following route, I am able to complete all 6 daily quests for the Knights of the Ebon Blade within 25 minutes.
First, fly to The Shadow Vault and pick up the following quests from the associated quest givers:
Vile (Abomination): “Vile Like Fire”

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Baron Silver (Blood Elf Death Knight): “Leave Our Mark” - He will provide an Ebon Blade Banner
The Leaper (Gist): “Shoot ‘Em Up”

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After you’ve obtained all 3 quests, fly to Death’s Rise in Icecrown at 20.3,47.7
Uzo Deathcaller (Troll Death Knight): “No Fly Zone”
Auroch’s Grimbane (Tauren Death Knight): “Intelligence Gathering”
Setaal Darkmender (Draenei Death Knight): "From Their Corpses Rise" - she will provide the Darkmender’s Tincture.