The Klaxxi are a faction in Dread Wastes that are sworn to protect the ideals of the Mantid Empire, even at the cost of killing their ruler. They are a council of mantid elders who have split off from the empire, working in defiance of the mantid queen. The pandaren know little about the mantid, less so the Klaxxi, viewing them as ruthless, but with a vast and advanced civilization. The Klaxxi quartermaster, [55, 35.6], can be found at Klaxxi'vess in the Dread Wastes.
At Honored, players can purchase Restorative Amber, which is like Major Dreamless Sleep Potion with a vanity effect. They can also buy a wide assortment of Justice Points gear and Blacksmithing recipes.
At Revered, players can purchase items level 489 necks, pants, and belts, as well as Amber Sledge of Klaxxi'vess. At Exalted, you can pick up vanity-themed items. Klaxxi Tabard is a tabard that only serves a cosmetic purpose, while Reins of the Amber Scorpion should especially make Alliance players happy, as it's a Horde-style scorpion mount. The most interesting reward at Exalted is a series of items level 463 weapons with distinctive amber-dipped looks for transmog.
To grind rep with The Klaxxi, you'll have to do a long questline in Dread Wastes starting with Psycho Mantid. This should get you to Honored, where there are at least 6 quests available from the Paragons you freed. At Revered, you free two more Paragons, who give you additional daily quests.
At Exalted, you can get an epic items level 489 ring from completing Shadow of the Empire. After you unlock all of the Klaxxi elders, you can request buffs from them, Enhancements and Augments.
Patch 5.0.4 (28-August-2012): Added