You can nicely farm reputaion in The Culling of Stratholme. Just do everything as usual to third boss Chrono-Lord Epoch - NPC - World of Warcraft . After you killed him go and wipe on next trash. Then run back in and dont talk to Arthas to continiue an event. There you have a road of mobs respawning in cca 5mins. The mobs are elite and non elites. If you cant find group to farm rep with, you can solo kill the non elite ones.
My first twocents.